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2021-07-13 City Council - Full PPW Agenda-2912
1 o Agenda Edmonds City Council PARKS AND PUBLIC WORKS COMMITTEE VIRTUAL ONLINE MEETING EDMONDS CITY COUNCIL MEETINGS WEB PAGE, HTTP://EDMONDSWA.IQM2.COM/CITIZENS/DEFAULT.ASPX, EDMONDS, WA 98020 JULY 13, 2021, 4:00 PM DUE TO THE CORONAVIRUS, MEETINGS ARE HELD VIRTUALLY USING THE ZOOM MEETING PLATFORM. TO VIEW OR LISTEN TO THE COMMITTEE MEETING IN ITS ENTIRETY, PASTE THE FOLLOWING INTO A WEB BROWSER USING A COMPUTER OR SMART PHONE: HTTPS://ZOOM. US/J/95798484261 OR JOIN BY DIAL -UP PHONE: US: +1 253 215 8782 WEBINAR ID: 957 9848 4261 COUNCIL COMMITTEE MEETINGS ARE WORK SESSIONS FOR THE COUNCIL AND CITY STAFF. COMMITTEE MEETING AGENDAS DO NOT INCLUDE AUDIENCE COMMENTS OR PUBLIC HEARINGS. CALL TO ORDER COMMITTEE BUSINESS 1. Taste Edmonds & Oktoberfest Event Contracts (10 min) 2. Report on Bids for Phase 2 Stormwater Replacement Project (10 min) 3. Presentation of a 128-SF Dedication at Northwest Corner of 4th Ave N & Daley St (5 min) 4. Presentation of Stormwater Management Code (ECDC 18.30) Update (20 min) ADJOURN Edmonds City Council Agenda July 13, 2021 Page 1 2.1 City Council Agenda Item Meeting Date: 07/13/2021 Taste Edmonds & Oktoberfest Event Contracts Staff Lead: Shannon Burley Department: Parks, Recreation & Cultural Services Preparer: Shannon Burley Background/History The Council authorizes Event Agreements on behalf the City of Edmonds. In 2020 all but one contracted special event (The Market) was cancelled due to COVID. Thus far Council has authorized the Market, 4th of July, Arts Festival and Spring Fest contracts for 2021. At this meeting City Staff is presenting Event Agreements for Taste Edmonds and Oktoberfest. Both events are to be held on the Frances Anderson Center Field in 2021. Staff Recommendation Staff recommendation is the City Council support the Event Agreement between the City of Edmonds and Chamber of Commerce for Taste Edmonds (attached) and the agreement between the City of Edmonds and the Edmonds Rotary Club for Oktoberfest (attached) and forward them to the July 20, 2021 Consent Agenda. Approval on consent would authorize the Mayor to sign the contracts. Narrative The Oktoberfest Agreement is very similar the event previously held on the Frances Anderson Center Field in 2019. Taste Edmonds is different in that it will be temporarily moved to the Frances Anderson Center Field while Civic Park is being renovated. Both event producers are required to follow the COVID guidelines set forth by the State of Washington and the Snohomish County Health Department at the time of the event. The contracts have been reviewed and approved by our internal team (Police, Fire, Public Works, Parks, Recreation & Cultural Services, Development Services, Human Resources (risk management) and Economic Development Departments) and approved as to form by the City Attorney. Both contracts require the promoters to comply with all noise ordinances, COVID guidelines and recycling/composting ordinances throughout the event. Further they are required to provide sufficient ADA parking, comply with Fire Marshall festival guidance and ensure the field be left in good condition. Taste Edmonds: A Seafair Sanctioned Community Event, Taste Edmonds will take place Friday, August 20 - Sunday, August 22. Taste Edmonds is the Chamber of Commerce's largest fundraising event each year with revenues supporting multiple free events such as Halloween, the Holiday Tree Lighting, 4th of July Parade and Fireworks. The mix of live music, beer garden and food has a long standing history in Edmonds. Packet Pg. 2 2.1 In 2021 the event will be reduced in size due to the renovation of Civic Park. The new event will feature food trucks / food vendors on 8th Avenue between Main St. and Dayton with live music and beer garden on the field. The event will be a 21+ event with restricted access and paid admission required. Oktoberfest: This two day event will be held on Friday September 24th and Saturday, September 25th in 2021. This will be the second Oktoberfest with the first being held in 2019 and the second being cancelled due to COVID. The event is run by the Edmonds Rotary Club is a ticketed event featuring folk music, beer tasting, wine, food and great activities for the entire family. The location of 8th Avenue between Main St and Dayton will be restricted to local access only and feature food trucks while the beer and tasting, stage and children's activities will be held on the field. Oktoberfest is an important fundraiser for the Edmonds Rotary Club's services projects such as student scholarships, Mika's Inclusive Playground at Civic Park and the Edmonds Waterfront Center. Attachments: 2021 Taste Edmonds Event Agreement 2021 Oktoberfest Event Agreement Packet Pg. 3 2.1.a EVENT AGREEMENT CITY OF EDMONDS, WASHINGTON AND GREATER EDMONDS CHAMBER OF COMMERCE August 18-23, 2021 The following is an agreement ("Agreement") between CITY OF EDMONDS (hereinafter referred to as the "City"), and the GREATER EDMONDS CHAMBER OF COMMERCE (hereinafter referred to as the "Chamber") (collectively, the "Parties"). WHEREAS, the Greater Edmonds Chamber of Commerce has for a number of years conducted a public event known as "Taste Edmonds" and proposes to do so again in 2021; and WHEREAS, the City Council finds that Taste Edmonds provides distinct benefits to local businesses and helps raise necessary funding to support events such as Halloween, 4th of July Fireworks and the Holiday Tree Lighting, while providing a unique recreational opportunity for its citizens; and WHEREAS, the City Council finds that such an event enhances tourism and promotes economic development as well as providing an opportunity for good clean fun to its citizens; and WHEREAS, the City Council finds that the considerations the City provides are more than adequately recompensed by the promises of the Edmonds Chamber of Commerce and the public benefit to be derived from this Agreement; NOW, THEREFORE, in consideration of the promises, covenants, conditions and performances set forth below, the Parties hereto agree as follows: 1. Responsibilities and Rights of City (certain Chamber obligations included). 1.1 The City will provide use of the Frances Anderson Center playfield, bandshell and plaza area behind the bandshell, 8th Avenue between Main Street and Dayton Street (See Exhibit A) and 8th Avenue between Main Street and Dayton Street and parking spaces on the North side of Dayton (See Exhibit B) (hereinafter referred to as the City -Provided Site") for use as the venue for Taste Edmonds (hereinafter referred to as the "Event"), and agrees to the following: 1.1.1 No Parking Signs placed on the West Side of 8th Avenue and on Dayton by Monday, August 16, 2021 at 8 a.m. 1.1.2 The Event setup will begin on Wednesday, August 18, 2021, at 8:00 a.m. Barricades, ADA and loading zone signs to be in place at 8:00 a.m. 1.1.3 The Event will run from 2:00 p.m. to 10:00 p.m. Friday, August 20, 2021; Noon — 10:00 p.m. Saturday August 21, 2021 and Noon — 8:00 p.m. on Sunday, August 22, 2021. 1.1.4 All surfaces listed will remain available to the Event until final cleanup, to be completed by Monday, August 23, 2021, at noon. Packet Pg. 4 2.1.a 1.1.5 The City will designate eight (8) additional handicapped parking spaces to be located along Main Street near the Event entrance (See Exhibit A). 1.2 The City may sprinkle the field prior to the Event to reduce dust. The playfield irrigation system will be turned off by 8:00 a.m. on August 18, 2021. The Chamber agrees to cover the infield dirt only. 1.3 All use and configuration of structures, booths and other permanent or temporary facilities used in the Event must comply with the "Food Vendor & Festival Requirements" set forth in Exhibit C, attached hereto and incorporated herein by this reference. Such structures, booths and facilities may be inspected and reviewed by the City Fire Chief, Police Chief, Building Official and Parks and Recreation Director or their designees to determine whether the facilities in use comply with the provisions of Exhibit C and state and local law, as well as to ensure that no lasting or permanent damage will be done to any public facility or property. 1.4 Edmonds Fire Marshal will inspect the facilities prior to the opening to the general public on or before 1:00 p.m., August 20, 2020, as the Parties will agree and note all potential problems. Prior to the opening of the Event, the Chamber will correct all problems related to fire safety. In the event that such problems are not corrected, the City may at its sole discretion cancel the Event or prohibit the attendance of the general public in certain areas, if in the opinion of the Fire Marshal and at the sole discretion of the City, any violation or other condition that threatens life, health or property has not been corrected. 1.5 Alcohol may be served, so long as the Chamber obtains all required state licenses and approvals to serve alcohol. These will be furnished to the City at least two (2) weeks in advance. 1.6 The City will provide safety barriers and road closure signs near the following two (2) locations for street closures required to contain the City -Provided Site described in Paragraph 1.1 and identified in Exhibit B, attached hereto and incorporated herein by this reference: 1.6.1 8th Avenue at Main Street, to close 8th Avenue 1.6.2 8th Avenue at Dayton Street, to close 8th Avenue 1.7 The City will provide eight (8) official handicapped parking signs and two (2) loading zone signs on Main Street as identified in Exhibit B. In addition, the North side of Dayton from 8th Ave west to the ADA parking spot will be marked "No Parking" August 18, 2021 at 8:00 a.m. through August 23, 2021 at Noon, as identified in Exhibit B. One local access only sign will be provide for the corner of Dayton and 8th Avenue. 1.8 The City may install Taste Edmonds street banners as provided by the Chamber at approved sites. The Chamber will obtain a Street Banner Permit and pay the required fee. 1.9 The City has the right to check the noise level of any amplified sound equipment or other source and require that the volume be reduced if it exceeds the safety limits recommended by the Seattle King County Department of Health or levels set forth in the ordinances of the City of Edmonds. Packet Pg. 5 2.1.a 1.10 The City will provide and oversee police supervision of the Event under the command of the Chief of Police or his/her designee. Police staffing levels and fees to be paid to the City will be mutually determined by the Chief of Police, or his/her designee, and the President and CEO of the Chamber. 1.11 The City will supply a list of acceptable compostable and recyclable food ware items and of suppliers for the compostable items. The City will provide signage for the on -site collection containers, and any additional containers, if needed. 1.12 The Chamber must supply power as needed. A Chamber representative and a City Public Works representative will meet prior to July 28, 2021, to draw up an exterior electrical plan. The City Electrician will have final say in all electrical matters. No ground penetrations are allowed unless authorized first by the City Electrician and City Parks Department. Any unauthorized ground penetrations may be subj ect to fine and/or damage cost recovery from the Chamber. 1.13 The Chamber is not authorized to fasten anything to the buildings, structures or trees. Doing to may result in damage cost recovery and/or fine. 2. Responsibilities and Rh!hts of Chamber 2.1 The Chamber will provide a Certificate of Insurance evidencing commercial general liability insurance written on an occurrence basis with limits no less than $2,000,000 combined single limit per occurrence and $4,000,000 aggregate for personal injury, bodily injury and property damage. In the event that the Chamber's employees and/or volunteers provide the service of alcohol at the Event, the Chamber's Commercial General Liability Insurance will also include host liquor liability coverage. However, if the Chamber contracts with a third -party vendor to provide all service of alcohol, the Chamber will be responsible for obtaining a Certificate of Insurance from the vendor confirming the vendor has Liquor Liability coverage, with limits no less than $1,000,000. The City will be named as an additional insured on the Chamber's Commercial General Liability insurance policy and the third -party vendor's Liquor Liability policy, if applicable, and a copy of the endorsement(s) naming the City as an additional insured will be attached to the Certificate of Insurance. The Chamber's liability insurance policy will contain a clause stating that coverage will apply separately to each insured against whom claim is made or suit is brought, except with respects to the limits of the insurer's liability. The insurance policy will contain, or be endorsed to contain, that the Chamber's insurance will be the primary insurance. Any insurance, self-insurance, or insurance pool coverage maintained by the City will be in excess of the Chamber's insurance and will not contribute to it. The Chamber will provide a certificate of insurance evidencing the required insurance before using the property described herein. Insurance will be placed with insurers with a current A.M. Best rating of not less than A:VII. 2.2 The Chamber agrees that Taste Edmonds is a public event. The Chamber further agrees that areas constituting the City -Provided Site that are covered under this Agreement, including but not limited to public rights of way, streets, sidewalks, parks, parking lots, gardens, meeting halls and squares, are traditional public forums. As a result, the Packet Pg. 6 2.1.a Chamber will permit citizens attending events open to the general public at the City - Provided Site during the Event to exercise therein their protected constitutional right to free speech without interference in a designated free speech zone that does not violate fire and ADA codes. 2.3 Chapter 6.80 of the Edmonds City Code ("Plastic Bag Reduction") restricts the use of single -use plastic checkout bags. The restrictions do not apply to plastic bags used to carry out cooked food or provided solely for produce, bulk food or meat. The Chamber will encourage its vendors to comply with the purposes of the ordinance by utilizing paper bags or encouraging the use of reusable totes whenever practicable. 2.4 Pursuant to the provisions of RCW 70.93.093 concerning event recycling, the Chamber will place clearly marked recycling containers throughout the Event area for the collection of aluminum, glass or plastic bottles or cans, and arrange for recycling services. 2.5 Chapter 6.95 of the Edmonds City Code ("Single -Use Plastic Utensils — Prohibition") prohibits the use of plastic straws, stirrers and cutlery at public events requiring a contract with the City. Therefore, food vendors at the Event will provide only certifiable compostable straws, stirrers and cutlery to Event participants. 2.6 Chapter 6.90 of the Edmonds City Code ("Noncompostable Food Service Containers — Prohibition") prohibits the use of noncompostable food service wares and packaging. Therefore, food vendors at the Event will provide compostable food service wares to package and present food to Event participants. Recyclable cans, bottles and cups continue to be acceptable for vendor use. The Chamber will provide for the on -site collection of compostable and recyclable materials from Event participants, using designated color -coded containers and will ensure that on -site containers are serviced properly and continually during the Event. A Chamber representative will meet with the City's Recycling Coordinator or representative prior to August 2, 2021, in order to be educated on the 3-container system to maximize diversion of compostable and recyclable materials from Event garbage, and the City will work to identify mutually agreed upon locations for food waste stations. These stations will be identified on Event maps and website. 2.7 The Chamber will defend, indemnify and hold the City, its officers, officials, employees and volunteers harmless from any and all claims, injuries, damages, losses or suits, including attorney fees, arising from or in connection with the Chamber's performance, or nonperformance, of this Agreement, except to the extent that claims, injuries, damages, losses or suits are caused by the sole negligence of the City, its officers, officials, employees or volunteers. This promise to indemnify and hold harmless will include a waiver by the Chamber of the immunity provided under Title 51 RCW, but only to the extent necessary to fully effectuate this promise. This provision will survive the termination or expiration of this Agreement. 2.8 The Chamber may in its discretion limit the participation of any vendor who produces duplication in order to adequately recognize limitations of space, failure to comply with applicable State or local health, liquor, or other requirements of law, and in order to Packet Pg. 7 2.1.a provide an adequate and interesting diversity compatible with the recreation of the citizens of Edmonds. 2.9 Neither the Chamber nor any of its officers, agents, or employees will discriminate in the provision of service under this Agreement against any individual, partnership, or corporation based upon race, religion, sex, creed, place of origin, or any other form of discrimination prohibited by federal, state or local law. 2.10 The Parties acknowledge that, pursuant to the provisions Chapter 70.160 RCW (herein after the "smoking ban"), smoking is prohibited in indoor areas, within 25 feet of vents or entrances and in outdoor areas where public employees of the City, and employees of any vendor at the Event or of the Chamber are required to be. This general description of the provisions of the statute is included for the purpose of reference and is not intended to expand or contract the obligations created by the smoking ban. The Chamber warrants that it will comply with the smoking ban and will utilize the services and advice of the Snohomish County Health District in assuring compliance during the Event described in this Agreement. 2.11 The Chamber will post "NO DOGS" signs on the City -Provided Site per Chapter 5.05 of the Edmonds City Code ("Animal Control"). The Chamber will notify vendors of this requirement as part of their registration instructions, and also inform vendors that this requirement will be enforced. This provision will not apply to service animals for the disabled. 2.12 The Chamber will ensure that all booths/beer garden/wine garden have the necessary state permits for serving and selling alcohol. The Chamber agrees to make its best effort to prevent service of alcohol to minors, including segregation of the beer garden and wine garden, posting security at the entrances of the beer garden and wine garden and checking identification in accordance with common practice. 2.13 The Chamber will obtain any copyright licenses necessary for presenting licensed live and recorded music. 2.14 The Chamber agrees to the following general open hours of Taste Edmonds and Beer / Wine Garden: Friday, August 20, 2021: 2:00 p.m. — 10:00 p.m. Last call 9:30 p.m., no service after 9:45 p.m. Saturday, August 21, 2021: 12:00 p.m. — 10:00 p.m. Last call 9:30 p.m., no service after 9:45 p.m. Sunday, August 22, 2021: 12:00 p.m. — 8:00 p.m. Last call 7:30 p.m., no service after 7:45 p.m. 2.15 The Chamber will provide any and all security services necessary during the night time hours (night time hours being defined as those hours which the Event is not in operation), sufficient to reasonably secure the area and facilities provided. The City will Packet Pg. 8 have no responsibility or liability for the provision of security services nor will it be liable for any loss or damage incurred by the Chamber or the participants in the Event. 2.16 The Chamber will provide a fire watch for all times the Event is open to the general public. The Fire Marshal or representative may inspect the Playfield and Amphitheater with the Chamber CEO or designated representative, prior to 12:00 p.m. Friday, August 20, 2021. 2.17 The Chamber will provide a sufficient number of portable sani-cans and wash stations. 2.18 The Chamber will provide fence installation and removal at the Frances Anderson Center to include along the center line of 8th Avenue for street closure, ensuring the East side of the street remains available to local access and emergency vehicles, and any Beer Garden and Wine Garden fencing as required by law. 2.19 The Chamber is responsible for contracting with appropriate vendors for electrical power. No power is available at the Frances Anderson Center field. 2.20 The Chamber will arrange for a walk-through with the City electrician and obtain approval for the accommodation of power and electricity needs. 2.21 Garbage service will be contracted and paid for by the Chamber. 2.22 The Chamber will be responsible for restoring the City -Provided Site to its original condition including steam cleaning and pressure washing whenever required for all hard surfaces impacted by the Event. A Chamber representative will meet with a member of the City's Parks and Recreation Department prior to August 18, 2021 and on August 23, 2021 to inspect the City -Provided Site to document the "original" and "post event" conditions of the Frances Anderson Center outside areas. 2.23 Cleanup areas include the City -Provided Site as described in paragraph 1.1 and all streets immediately surrounding the Event perimeter. 2.24 All garbage to the size of a cigarette butt, debris, litter, equipment, and any and all other items made necessary by or used in the provision of the Event will be picked up and removed by 12:00 noon, Monday, August 23, 2021. 2.25 The Chamber will submit a cleaning/damage deposit of One Thousand Five Hundred Dollars ($1,500.00) to the City prior to Monday, July 19, 2021. The deposit will be refunded to the Chamber if, upon inspection, all is in order, or a prorated portion thereof as may be necessary to reimburse the City for loss or cleaning costs. 2.26 The Chamber will pay the City One Thousand Two Hundred Fifty Dollars ($1,250.00) for the use of the City -Provided Site prior to Monday, July 19, 2021, and will reimburse the City for the actual costs of supplies or services furnished by the City, unless otherwise established, within thirty (30) days of mailing of a final bill by the City. 2.27 The Chamber will insure that: Packet Pg. 9 2.1.a 2.27.1 Kilns, barbecues, forges and other sources of heat will be insulated from turfed areas to prevent the heat from killing the grass and sterilizing the soil. All heat producing appliances will be approved by the Fire Department and may require conditions for their acceptable use. Food vendor installations will be inspected prior to the Event opening. Tarps, tents, canopies and covers will be listed and labeled for flame resistance. 2.27.2 Vehicles will only be allowed on the grass areas to load and unload, with adjacent streets used for parking during the Event. 2.27.3 The Chamber will notify all individual residents of the affected areas of 8th Avenue and provide general notice to all the citizens of the closure of 8th Avenue. 2.27.4 Tents must be held down with sandbags and not stakes. 3. General Provisions. 3.1 Entire agreement, integration and amendment. This Agreement contains the entire agreement and understanding between the Parties relating to the rights and obligations created hereby, and supersedes all prior and contemporaneous negotiations, understandings, and agreements, written or oral, between the Parties. Any prior discussions or understandings are deemed merged with the provisions herein. This Agreement will not be amended, assigned or otherwise changed or transferred except in writing with the express written consent of the Parties hereto. Any action to interpret or enforce this Agreement will be brought before the Superior Court of Snohomish County, Washington, and the Parties agree that, as between them, all matters will be resolved in that venue. 3.2 Force majeure. The Parties will not be liable for failure to perform or delay in performance due to fire, flood, strike or other labor difficulty, act of God, act of any governmental authority, riot, embargo, fuel or energy shortage, car shortage, wrecks or delays in transportation, or due to any other cause beyond the Parties' reasonable control. In the event of delay in performance due to any such cause, the date of delivery or time for completion will be extended by a period of time reasonably necessary to overcome the effect of such delay. 3.3 Relationship between the Parties. Nothing in this Agreement will be interpreted to or in fact create an agency or employment relationship between the Parties. No officer, official, agent, employee or representative of the Chamber will be deemed to be the same of the City for any purpose. The Chamber alone will be solely responsible for all acts of its officers, officials, agents, employees, representatives and subcontractors during the performance of this Agreement. 3.4 Compliance with laws. The Chamber in the performance of this Agreement will comply with all applicable federal, state and local laws and ordinances, including guidelines and requirements relating to COVID-19. The most recent information regarding the applicable state and federal guidelines and requirements relating to the COVID-19 pandemic can be found on the Washington State coronavirus response webpage at www.coronavirus.wa.gov and on the Centers for Disease Control and Prevention website at www.cdc.gov. The Chamber will consult this information before and during the course of the Event to ensure that the latest guidelines and requirements are promptly implemented. 3.5 Non -Waiver. Waiver by the City of any provision of this Agreement or any time limitation provided for in this Agreement shall not constitute a waiver of any other provision. Packet Pg. 10 2.1.a 3.6 Termination. Each and every term and condition herein set forth and contained in this Agreement are expressly made terms, covenants, agreements and conditions, and a breach of any one of them by the Chamber shall constitute a breach of this Agreement. In the event the Chamber fails to comply with any of the terms, covenants, agreements or conditions of this Agreement, or in the event the Chamber violates any local, city, county, state, or federal law, in connection with the Event, upon giving the Chamber twenty-four (24) hours' advance written notice, the City may terminate this Agreement. Provided, the Parks, Recreation & Cultural Services Director may order the Chamber to cease operation of the Event hereunder immediately at any time should the Parks, Recreation & Cultural Services Director determine that the Event is detrimental to public safety, health, or welfare. Such a determination may be made in relation to COVID-19 or to any other public safety, health or welfare issue. In the event of termination of this Agreement, all the rights, licenses, and privileges herein contained shall be terminated, the Chamber will have no further rights hereunder, and the City may require the immediate removal of all property of the Chamber and its vendors from the City -Provided Site. DATED this day of CITY OF EDMONDS: Mike Nelson, Mayor ATTEST/AUTHENTICATED: Scott Passey, City Clerk APPROVED AS TO FORM: Office of the City Attorney 2021. GREATER EDMONDS CHAMBER OF COMMERCE: Greg Urban, President and CEO Packet Pg. 11 2.1.a Fo Exhibit A 2+021 Taste Edmonds Site Plan ",1. SIR . ^� , � 4 5!.•' El r�^�'"� ,0 x x 1 x x [n c7 m m(� o @ @ @ w m m 71 o r 0 Vf o n n m@@ @ @ O Ru Q fa fa C] � _ A o N 3 @ @ n n ff1 rif x (D Z3 rf) n @ m w N V L C O U c m W N d O Y O 06 N C O W d N M t7 9 Packet Pg. 12 2.1.a Sno-Isle Library June2021 Exhibit B 2021 Taste Edmonds Traffic Control PLan EDMONDS ST no No Ea�� RikGF.aW'u� P�6 p. PU. A Frances Anderson Anderson Center Field Center No parking August 18 at 8 am - August 23 at Noon Q 2 H 00 MAPLE ST In ILL! a = ALDER ST W4LNUT ST Z w a C) Water Barricades and Barricade Signs provided by Public Works. Closed to all traffic. Water Barricades and Barricade Signs provided by Public Works. Local Access Only ■ Road Closure Barricade Reserved for ADA g Parking Signs Food Trucks West side only NO Loading Zone Only Signs 1 0 No Parking Signs in place by Mon Aug 16 10 Packet Pg. 13 2.1.a Exhibit C South County Fire' Food Vendor & Festival Requirements Fire Lane - A 20 ft Fire Lane must be maintained for emergency vehicle access. - Unobstructed access to Fire hydrants shall be maintained at all times. The fire department shall not be deterred or hindered from gaining immediate access for rendering aid or to fire protection equipment or fire hydrants (IFC 507.5.4) Tents and Other Membrane Structures - All tents, canopies, and other membrane structures erected shall meet the requirements of the current edition of NFPA 701 and the IFC Section 3103 and 3104 and shall be labeled fire resistive. - Tents need to be less than 400 sq ft or additional permit maybe required. - Inflatable play equipment and all membrane structures shall be properly installed per the manufacturer instructions. Fire Extinguishers - 5-lbs. Portable ABC type extinguisher is required in all booths with current annual inspection/service tag attached. - Booths with deep fat fryers also require a Class "K" rated fire extinguisher with current annual inspection/service tag attached. - Hood suppression systems MUST have current inspection documentation. - Keep fire extinguishers accessible and conspicuous. Cooking - No candles or open flame devices like tiki torches. - No flaming food. - Barbecue pits need a 10' separation from combustibles and portable FE. - Open flame from cooking devices shall be enclosed in such a manner as to prevent the flame from contacting any combustible material and shall be placed on a non-combustible surface. - All combustibles shall be kept away from heat sources. - No cooking appliances/heat sources will be within physical reach of the general public. Flertriral Cords - Minimum size 12-2 with ground UL approved outdoor rated from power feed source, 14-2 with ground UL approved is allowed elsewhere. - All cords shall be free of splices, cuts or breaks in outer sheathing. - UL or other approved Strip Plugs with integral circuit breaker are the only allowed power tap/adapter. Booth Construction - Cooking booth construction shall be labeled fire resistive. - Non -rated blue, green or brown plastic tarps are not allowed over cooking areas. Rubbish - Keep combustible rubbish in closed containers. - Cardboard boxes are rubbish/not rubbish containers. - Rubbish containers larger than 40 gallons must be labeled fire -resistive. Fuel Use/Storage - All tanks/cylinders (whether in use or storage) must be secured to avoid falling and damaging the valve assembly. - No smoking in or around cooking/fuel use or storage areas. - Store tanks/cylinders upright so pressure relief valve is in vapor space. - Fuel tank/cylinder storage/Use is limited to one day's supply, quantity at the discretion of Fire Marshal. Fire District 1 (South County Fire), 12425 Meridian Avenue S, Everett, WA 98208 / 425-551-1200 / www.firedistrictl.org 11 Packet Pg. 14 2.1.b EVENT AGREEMENT CITY OF EDMONDS, WASHINGTON AND EDMONDS ROTARY CLUB September 24 — 26, 2021 The following is an agreement ("Agreement") between the CITY OF EDMONDS (hereinafter referred to as the "City"), and the EDMONDS ROTARY CLUB (hereinafter referred to as the "Rotary") (collectively, the "Parties"). WHEREAS, the Edmonds Rotary Club has in the past conducted a public event known as "Edmonds Rotary Oktoberfest" (hereinafter referred to as the "Event") and proposes to do so again in 2021; and WHEREAS, the City Council finds that the Event will enhance tourism and promote economic development, as well as providing an opportunity for good clean fun to its citizens; and WHEREAS, the City Council finds that the considerations the City provides are more than adequately recompensed by the promises of the Edmonds Rotary Club and the public benefit to be derived from this Agreement; NOW, THEREFORE, in consideration of the promises, covenants, conditions and performances set forth below, the Parties hereto agree as follows: 1. Responsibilities of the City (certain Rotary obligations included). 1.1 The City will provide use of the Playfield, and the Bandshell at the Frances Anderson Center and 8th Avenue between Main Street and Dayton Street (See Site Map at Exhibit A & Traffic Control Plan at Exhibit B) (hereinafter referred to as the "City - Provided Site") for use as the venue for Oktoberfest (hereinafter referred to as the "Event"), and agrees to the following: 1.1.1 No Parking Signs placed on the West Side of 8tn Avenue and on Dayton for dumpster delivery by Wednesday, September 22, 2021 at 8 a.m. 1.1.2 The Event setup will begin on Friday, September 24, 2021 at 8:00 a.m.; barricades, ADA and loading zone signs to be in place by 8:00 a.m. 1.1.3 The Event will run from 4:00 p.m. to 10:00 p.m. on Friday, September 24, 2021 and 12:00 p.m. to 10:00 p.m. on Saturday, September 25, 2021. 1.1.4 The Frances Anderson Playfield and Bandshell will be used for the stage, beer festival, events and craft booths. The section of 8th Avenue described above will be utilized as an area for food concessions and eating tables. 1.1.5 All surfaces listed will remain available to the Rotary until final cleanup, to be completed by Sunday, September 26, 2021 at 12:00 noon. Packet Pg. 15 2.1.b 1.2 The City may sprinkle the field prior to the Event to reduce dust. The playfield irrigation system will be turned off by 8:00 a.m. on September 24, 2021. The Rotary agrees to cover the infield dirt only. 1.3 The City will provide up to fifteen (15) picnic tables and up to ten (10) garbage cans around the outside area. The Rotary will also provide crew members to assist with the moving and placement of tables and garbage cans. The Rotary will be responsible for emptying the trash cans. The City will supply backup trash bags. 1.4 All use and configuration of structures, booths and other permanent or temporary facilities used in the Event must comply with the "Food Vendor & Festival Requirements" set forth in Exhibit C, attached hereto and incorporated herein by this reference. Such structures, booths and facilities may be inspected and reviewed by the City Fire Chief, Police Chief, Building Official and the Parks, Recreation & Cultural Services Director or their designees to determine whether the facilities in use comply with the provisions of Exhibit C and state and local law, as well as to ensure that no lasting or permanent damage will be done to any public facility or property. 1.5 Edmonds Fire Marshal may inspect the facilities prior to the opening to the general public on or before 2:00 p.m., September 24, 2021, as the Parties will agree, and note all potential problems. Prior to the opening of the Event, the Rotary will correct all problems related to fire safety. In the event that such problems are not corrected, the City may at its sole discretion cancel the Event or prohibit the attendance of the general public in certain areas, if in the opinion of the Fire Marshal and at the sole discretion of the City, any violation or other condition that threatens life, health or property has not been corrected. 1.6 Alcohol may be served, so long as the Rotary obtains all required state licenses and approvals to serve alcohol. These will be furnished to the City at least two (2) weeks prior to the Event. 1.7 The City will provide safety barriers at the following two (2) locations for street closures required to contain the City -Provided Site described in Paragraph 1.1 and identified in Exhibit B, attached hereto and incorporated herein by this reference: 1.7.1 8th Avenue at Main Street, to close 8th Avenue 1.7.2 8th Avenue at Dayton Street, to close 8m Avenue (local access only) 1.8 The Rotary will work with the City to identify ADA parking stalls. The City will provide official handicapped parking signs. One load/unload space each will be marked on Dayton and Main Street. 1.9 The City may install Edmonds Oktoberfest street banners as provided by the Rotary at approved sites. The Rotary will obtain a Street Banner Permit and pay the required fee. 1.10 The City has the right to check the noise level of any amplified sound equipment or other source and require that the volume be reduced if it exceeds the safety limits Packet Pg. 16 2.1.b recommended by the Seattle King County Department of Health or levels set forth in the ordinances of the City of Edmonds. 1.11 The City will provide and oversee police supervision of the Event under the command of the Chief of Police or his/her designee. Police staffing levels and fees to be paid to the City will be mutually determined by the Chief of Police, or his/her designee, and the President of the Rotary. 1.12 The City will supply a list of acceptable compostable and recyclable food ware items and of suppliers for the compostable items. The City will provide signage for the on - site collection containers, and any additional containers, if needed. 1.13 The Rotary must supply power as needed. There will be no temporary PUD hookups or power poles installed for this event, it will run off of generator power. A Rotary representative and a City Public Works representative will meet prior to September 10, 2021, to draw up an exterior electrical plan. The City Electrician will have final say in all electrical matters. (No ground penetrations are allowed unless authorized first by the City Electrician and City Parks Department). Any unauthorized ground penetrations may be subject to fine and/or damage cost recovery from the Rotary. 1.14 The Rotary is not authorized to fasten anything to the buildings, structures or trees. Doing so may result in damage cost recovery and/or fine. 2. Responsibilities and Rights of the Rotary 2.1 The Rotary will operate the Edmonds Oktoberfest, and neither the Rotary nor any of its officers, agents or employees will discriminate in the provision of service under this Agreement against any individual, partnership, or corporation based upon race, religion, sex, creed, place of origin, or any other form of discrimination prohibited by federal, state or local law. 2.2 The Parties acknowledge that, pursuant to the provisions of Chapter 70.160 RCW (herein after the "smoking ban"), smoking is prohibited in indoor areas, within 25 feet of vents or entrances and in outdoor areas where public employees of the City and employees of any vendor at the Event or of the Rotary are required to be. This general description of the provisions of the statute is included for the purpose of reference and is not intended to expand or contract the obligations created by the smoking ban. The Rotary warrants that it will comply with the smoking ban and will utilize the services and advice of the Snohomish County Health District in assuring compliance during the Event described in this Agreement. 2.3 The Rotary agrees that the Edmonds Oktoberfest is a public event. The Rotary further agrees that areas constituting the City -Provided Site that are covered under this Agreement, including but not limited to public rights of way, streets, sidewalks, parks, parking lots, and gardens, are traditional public forums. As a result, the Rotary will permit citizens attending events open to the general public at the City -Provided Site during the Event to exercise therein their protected constitutional right to free Packet Pg. 17 2.1.b speech without interference in a designated free speech zone that does not violate fire and ADA codes. 2.4 Chapter 6.80 of the Edmonds City Code ("Plastic Bag Reduction") restricts the use of single -use plastic checkout bags. The restrictions do not apply to plastic bags used to carry out cooked food or provided solely for produce, bulk food or meat. The Rotary will encourage its vendors to comply with the purposes of the ordinance by utilizing paper bags or encouraging the use of reusable totes whenever practicable. 2.5 Pursuant to the provisions of RCW 70.93.093, concerning event recycling, the Rotary will place clearly marked recycling containers throughout the Event area for the collection of aluminum cans, glass or plastic bottles from event participants, and arrange for recycling services. 2.6 Chapter 6.95 of the Edmonds City Code ("Single -Use Plastic Utensils — Prohibition") prohibits the use of plastic straws, stirrers and cutlery at public events requiring a contract with the City. Therefore, food vendors at the Event will provide only certifiable compostable straws, stirrers and cutlery to Event participants. 2.7 Chapter 6.90 of the Edmonds City Code ("Noncompostable Food Service Containers — Prohibition") prohibits the use of noncompostable food service wares and packaging. Therefore, food vendors at the Event will provide compostable food service wares to package and present food to Event participants. Recyclable cans, bottles and cups continue to be acceptable for vendor use. The Rotary will provide for the on -site collection of compostable and recyclable materials from Event participants, using designated color -coded containers and will ensure that on -site containers are serviced properly and continually during the Event. A Rotary representative will meet with the City's Recycling Coordinator or representative prior to September 10, 2021, in order to be educated on the 3-container system to maximize diversion of compostable and recyclable materials from Event garbage, and the City will work to identify mutually agreed upon locations for food waste stations. These stations will be identified on Event maps and website. 2.8 The Rotary may in its discretion limit the participation of any vendor who produces duplication in order to adequately recognize limitations of space, failure to comply with applicable State or local health, liquor, or other requirements of law, and in order to provide an adequate and interesting diversity compatible with the recreation of the citizens of Edmonds. 2.9 The Rotary will be responsible for restoring the City -Provided Site to its original condition. A Rotary representative will meet with a member of the City's Parks and Recreation Department on September 23, 2021 to inspect the City -Provided Site to document the "original" and "post event" conditions of the City -Provided Site and surrounding areas. 2.10 The Rotary will provide a sufficient number of portable sani-cans and wash stations. Packet Pg. 18 2.1.b 2.11 The Rotary will be responsible for all required city and state permits. The Rotary will submit all required application(s) and fees(s) for the Street Banner Permits provided for by this Agreement. All permits will be arranged through a designated representative of the City. The Rotary is responsible for obtaining any necessary permits for serving alcohol on the premises from the state. 2.12 The Rotary will ensure that all boothsibeer garden/wine garden have the necessary state permits for serving and selling alcohol. The Rotary agrees to make its best effort to prevent service of alcohol to minors, including segregation of the beer garden and wine garden, posting security at the entrances of the beer garden and wine garden and checking identification in accordance with common practice. 2.13 The Rotary will obtain any copyright licenses necessary for presenting licensed live and recorded music. 2.14 The provisions of Chapter 5.05 of the Edmonds City Code ("Animal Control") apply to the City -Provided Site. ECC 5.05.060 prohibits dogs, whether on leash or off leash from being present on City playfields. The Parks, Recreation & Cultural Services Director will provide a temporary exemption to this prohibition and allow dogs to be on leash at the Event. The Rotary will ensure that: (a) dogs remain on leash or under other manner of restraint at all times while on the City -Provided Site; (b) dogs do not enter the playground area; and (c) all dog waste is removed from the site. The Rotary will notify Police of any aggressive dog behavior. The Parks, Recreation & Cultural Services Director retains the right to suspend this temporary exemption at any time. 2.15 Garbage service will be contracted and paid for by the Rotary. 2.16 The Rotary will be responsible for clean-up of the City -Provided Site as follows: A. Restore all areas to their original condition. B. Pick up all trash and remove all items and equipment related to the Event by 12:00 noon, September 26, 2021 (including grounds and buildings). C. Power wash the following: a. All paved food concession areas; and b. All pedestrian walkways/steps around amphitheater. D. Install drain guards on all affected storm drains prior to the beginning of the Event, and remove them after clean-up is complete. Drain guards will be provided by the City. Power washed materials (litter, etc.) must be collected and disposed of and not pushed to adjacent areas. E. Pick up and remove all garbage to the size of a cigarette butt, debris, litter, equipment, and any and all other items made necessary by or used in the provision of the Event by 12:00 noon, Sunday, September 26, 2021. F. Disposal of waste water will be according to the City policy using grease traps provided, cleaned, and picked up by the Rotary. Packet Pg. 19 2.17 A final inspection of the Event area will be conducted by the City Parks Maintenance Division to determine if all areas are clean and returned to their original condition. 2.18 The Rotary will submit a cleaning/damage deposit of One Thousand Five Hundred dollars ($1,500.00) to the City prior to Tuesday, September 7, 2021. The deposit will be refunded to the Rotary if, upon inspection, all is in order, or a prorated portion thereof as may be necessary to reimburse the City for loss or cleaning costs. 2.19 The Rotary will pay the City Seven Hundred Fifty dollars ($750.00) for the use of the City -Provided Site prior to Tuesday, September 6, 2021, and will reimburse the City for the actual costs of supplies or services furnished by the City, unless otherwise established, within thirty (30) days of mailing of a final bill by the City. 2.20 The Rotary will provide a fire watch for all times the Event is open to the general public. The Fire Marshall or representative may inspect the City -Provided Site with the Rotary President, or designated representative, prior to 12:00 noon on September 24, 2021. 2.21 The Rotary will insure that: A. Kilns, barbecues, forges and other sources of heat will be insulated from turfed areas to prevent the heat from killing the grass and sterilizing the soil. All heat producing appliances will be approved by the Fire Department and may require conditions for their acceptable use. Food vendor installations will be inspected prior to the Event opening. Tarps, tents, canopies and covers will be listed and labeled for flame resistance. B. Vehicles will only be allowed on turfed areas to load and unload, with adjacent streets used for parking during the Event. C. The Rotary will notify all individual residents of the affected areas of 8th Avenue and provide general notice to all the citizens of the closure of 8th Avenue. D. Tents are held down with sandbags and not stakes. 2.22 The Rotary will defend, indemnify and hold the City, its officers, officials, employees and volunteers harmless from any and all claims, injuries, damages, losses or suits, including attorney fees, arising from or in connection with the Rotary's performance, or nonperformance, of this Agreement, except to the extent that claims, injuries, damages, losses or suits are caused by the sole negligence of the City, its officers, officials, employees or volunteers. This promise to indemnify and hold harmless will include a waiver by the Rotary of the immunity provided under Title 51 RCW, but only to the extent necessary to fully effectuate this promise. This provision will survive the termination and/or expiration of this Agreement. 2.23 The Rotary will provide a Certificate of Insurance evidencing insurance written on an occurrence basis with limits no less than $2,000,000 combined single limit per occurrence and $4,000,000 aggregate for personal injury, bodily injury and property Packet Pg. 20 2.1.b damage. In the event that the Rotary's employees and/or volunteers provide the service of alcohol at the Event, the Rotary's Commercial General Liability Insurance will also include host liquor liability coverage. However, if the Rotary contracts with a third -parry vendor to provide all service of alcohol, the Rotary will be responsible for obtaining a Certificate of Insurance from the vendor confirming the vendor has Liquor Liability coverage, with limits no less than $1,000,000. The City will be named as an additional insured on the Rotary's Commercial General Liability insurance policy and the third -parry vendor's Liquor Liability policy, if applicable, and a copy of the endorsement (s) naming the City as an additional insured will be attached to the Certificate of Insurance. The Rotary's liability insurance policy will contain a clause stating that coverage will apply separately to each insured against whom claim is made or suit is brought, except with respects to the limits of the insurer's liability. The insurance policy will contain, or be endorsed to contain that the Rotary's insurance coverage will be primary insurance. Any insurance, or insurance pool coverage, maintained by the City will be in excess of the Rotary's insurance and will not contribute to it. The Rotary will provide a certificate of insurance evidencing the required insurance before using the premises described herein. Insurance will be placed with insurers with a current A.M. Best rating of not less than A:VII. 2.24 The Rotary agrees to the following general open hours for Edmonds Oktoberfest: Friday, September 24, 2021 4:00 p.m. — 10:00 p.m. Saturday, September 25, 2021 12:00 p.m. — 10:00 p.m. The Rotary agrees to keep the hours of operation in the Beer Garden / Wine Garden within the following schedule: Friday, September 24, 2021 4:00 p.m. — 10:00 p.m. Last call 9:30 p.m., no service after 9:45 p.m. Saturday, September 25, 2019 12:00 p.m. — 10:00 p.m. Last call 9:30 p.m., no service after 9:45 p.m. 2.25 The Rotary will provide any and all security services necessary during the night time hours (night time hours being defined as those hours which the Event is not in operation), sufficient to reasonably secure the area and facilities provided. The City will have no responsibility or liability for the provision of security services, nor will it be liable for any loss or damage incurred by the Rotary or the participants in the Event. 2.26 The Rotary will provide fence installation and removal at the Beer Garden / Wine Garden, if installing fence on 8th Avenue Rotary will ensure the fence runs along the center line of the street allowing for vehicle access on the East side of the street. 2.27 The Rotary is responsible for contracting with appropriate vendors for electrical power. No power is available at the Frances Anderson Center field. 2.28 The Rotary will arrange for a walk-through with the City Electrician and obtain approval for the accommodation of power and electricity needs. Packet Pg. 21 2.1.b 2.29 All requests for additional services for, and concerns about, the Event will be directed by the Rotary President to the City's designated representative, the Parks, Recreation & Cultural Services Deputy Director, who may be contacted at 425-771-0230. 3. General Provisions 3.1 Entire agreement, integration and amendment. This Agreement contains the entire agreement and understanding between the Parties relating to the rights and obligations created hereby, and supersedes all prior and contemporaneous negotiations, understandings, and agreements, written or oral, between the Parties. Any prior discussions or understandings are deemed merged with the provisions herein. This Agreement will not be amended, assigned or otherwise changed or transferred except in writing with the express written consent of the Parties hereto. Any action to interpret or enforce this Agreement will be brought before the Superior Court of Snohomish County, Washington, and the Parties agree that, as between them, all matters will be resolved in that venue. 3.2 Force majeure. The Parties will not be liable for failure to perform or delay in performance due to fire, flood, strike or other labor difficulty, act of God, act of any governmental authority, riot, embargo, fuel or energy shortage, car shortage, wrecks or delays in transportation, or due to any other cause beyond the Parties' reasonable control. In the event of delay in performance due to any such cause, the date of delivery or time for completion will be extended by a period of time reasonably necessary to overcome the effect of such delay. 3.3 Relationship between the Parties. Nothing in this Agreement will be interpreted to or in fact create an agency or employment relationship between the Parties. No officer, official, agent, employee or representative of the Rotary will be deemed to be the same of the City for any purpose. The Rotary alone will be solely responsible for all acts of its officers, officials, agents, employees, representatives and subcontractors during the performance of this Agreement. 3.4 Compliance with laws. The Rotary in the performance of this Agreement will comply with all applicable federal, state and local laws and ordinances, including guidelines and requirements relating to COVID-19. The most recent information regarding the applicable state and federal guidelines and requirements relating to the COVID-19 pandemic can be found on the Washington State coronavirus response webpage at www.coronavirus.wa.gov and on the Centers for Disease Control and Prevention website at www.cdc.gov. The Rotary will consult this information before and during the course of the Event to ensure that the latest guidelines and requirements are promptly implemented. 3.5 Non -Waiver. Waiver by the City of any provision of this Agreement or any time limitation provided for in this Agreement will not constitute a waiver of any other provision. 3.6 Termination. Each and every term and condition herein set forth and contained in this Agreement are expressly made terms, covenants, agreements and conditions, and a breach of any one of them by the Rotary will constitute a breach of this Agreement. In the event the Rotary fails to comply with any of the terms, covenants, agreements or conditions of this Agreement, or in the event the Rotary violates any local, city, county, state, or federal law, in connection with the Event, upon giving the Rotary twenty-four (24) hours' advance written notice, the City may terminate this Packet Pg. 22 2.1.b Agreement. Provided, the Parks, Recreation & Cultural Services Director may order the Rotary to cease operation of the Event hereunder immediately at any time should the Parks, Recreation & Cultural Services Director determine that the Event is detrimental to public safety, health, or welfare. Such a determination may be made in relation to COVID-19 or to any other public safety, health or welfare issue. In the event of termination of this Agreement, all the rights, licenses, and privileges herein contained will be terminated, the Rotary will have no further rights hereunder, and the City may require the immediate removal of all property of the Rotary and its vendors from the City -Provided Site. DATED this day of CITY OF EDMONDS: Mike Nelson, Mayor ATTEST/ AUTHENTICATED: Scott Passey, City Clerk APPROVED AS TO FORM: Office of the City Attorney 2021. EDMONDS ROTARY CLUB: Libby Freese, Edmonds Rotary Club Treasurer Date: Packet Pg. 23 Exhibit A: Site Map Q Packet Pg. 24 Exhibit B Traffic Control Plan EDMONDS ST Z a W Q BELL ST—Co I MAIN SiEl FWater Barricades and Barricade Signs provided by Public Works. Closed to all traffic. Sno-Isle Frances Anderson Library Anderson Center Field Center Water Barricades and Barricade Signs © © provided by Public Works. Local Access Only ©AYTON ST U) W a co MAPLE ST - �- co �I > Q � 2 W F- > Q T ALDER ST WALNUT ST May 2020 ■ Road Closure Barricade Reserved for ADA g Parking Signs Food Trucks West side only Packet Pg. 25 Exhibit C South County Fire' Food Vendor & Festival Requirements Fire Lane - A 20 ft Fire Lane must be maintained for emergency vehicle access. - Unobstructed access to Fire hydrants shall be maintained at all times. The fire department shall not be deterred or hindered from gaining immediate access for rendering aid or to fire protection equipment or fire hydrants (IFC 507.5.4) Tents and Other Membrane Structures - All tents, canopies, and other membrane structures erected shall meet the requirements of the current edition of NFPA 701 and the IFC Section 3103 and 3104 and shall be labeled fire resistive. - Tents need to be less than 400 sq ft or additional permit maybe required. - Inflatable play equipment and all membrane structures shall be properly installed per the manufacturer instructions. Fire Extinguishers - 5-lbs. Portable ABC type extinguisher is required in all booths with current annual inspection/service tag attached. - Booths with deep fat fryers also require a Class "K" rated fire extinguisher with current annual inspection/service tag attached. - Hood suppression systems MUST have current inspection documentation. - Keep fire extinguishers accessible and conspicuous. Cooking - No candles or open flame devices like tiki torches. - No flaming food. - Barbecue pits need a 10' separation from combustibles and portable FE. - Open flame from cooking devices shall be enclosed in such a manner as to prevent the flame from contacting any combustible material and shall be placed on a non-combustible surface. - All combustibles shall be kept away from heat sources. - No cooking appliances/heat sources will be within physical reach of the general public. Flertriral Cords - Minimum size 12-2 with ground UL approved outdoor rated from power feed source, 14-2 with ground UL approved is allowed elsewhere. - All cords shall be free of splices, cuts or breaks in outer sheathing. - UL or other approved Strip Plugs with integral circuit breaker are the only allowed power tap/adapter. Booth Construction - Cooking booth construction shall be labeled fire resistive. - Non -rated blue, green or brown plastic tarps are not allowed over cooking areas. Rubbish - Keep combustible rubbish in closed containers. - Cardboard boxes are rubbish/not rubbish containers. - Rubbish containers larger than 40 gallons must be labeled fire -resistive. Fuel Use/Storage - All tanks/cylinders (whether in use or storage) must be secured to avoid falling and damaging the valve assembly. - No smoking in or around cooking/fuel use or storage areas. - Store tanks/cylinders upright so pressure relief valve is in vapor space. - Fuel tank/cylinder storage/Use is limited to one day's supply, quantity at the discretion of Fire Marshal Fire District 1 (South County Fire), 12425 Meridian Avenue S, Everett, WA 98208 / 425-551-1200 / www.firedistrictl.org Packet Pg. 26 2.2 City Council Agenda Item Meeting Date: 07/13/2021 Report on Bids for Phase 2 Stormwater Replacement Project Staff Lead: Rob English Department: Engineering Preparer: Sydney Hall Background/History None Staff Recommendation Staff will provide the bid results at the committee meeting and make a recommendation on the possible award of the Phase 2 Storm Replacement Project. Narrative This project is part of the City's program to replace and upgrade existing storm lines at various locations around the City that are reaching the end of their useful service life, are undersized and unable to meet current requirements, or has some other existing system deficiency. The project will replace storm piping, and structures on Maple St from 6th to 7th and the alley between Maple and Alder. On June 17 and June 24, 2021 the project was advertised for construction bids. Construction bids are due by 2:00 p.m. on July 8th, 2021, which may provide an opportunity to award the project at the July 20th City Council Meeting. The bid results, project budget and a possible recommendation to award the Phase 2 contract will be provided at the July 13th Committee meeting. Construction is expected to begin in August and be completed by October of this year. The project costs are being funded by the 422 Utility Funds. Attachments: Exhibit 1 Phase 2 Storm map Packet Pg. 27 City of Edmonds Mapbook 2.3 City Council Agenda Item Meeting Date: 07/13/2021 Presentation of a 128-SF Dedication at Northwest Corner of 4th Ave N & Daley St Staff Lead: Rob English Department: Engineering Preparer: Sydney Hall Background/History None Staff Recommendation Forward item to the consent agenda for approval at the July 20th City Council meeting. Narrative The City is currently reviewing a building permit application for a single-family residence at 327 Daley Street located at the NW corner of 4t" Ave N and Daley Street. The existing public sidewalk at this corner falls within the boundary lines of the private property and with the proposed development the property owner will dedicate 128sf of property to the City as right-of-way. Following dedication, the sidewalk will be located entirely within the public right-of-way. Following council approval, the street dedication will be recorded through a deed document, which will occur prior to issuance of certificate of occupancy for the single-family residential development. Attachments: Attachment 1 Vicinity Map Attachment 2 Site Plan Packet Pg. 29 2.3a City of Edmonds Vicinity Map - 327 Daley St r �� :ca `roj • �r. � � w / � [} Ls� L L 0 126.30 252.6 Feet 188.1 This ma is a user generated static output from an Internet mapping site and is 2,257 P � B P PP B reference only. Data layers that appear on this map may or may not be accura WGS 1984 Web Mercator_ Auxiliary —Sphere current, or otherwise reliaE © City of Edmonds THIS MAP IS NOT TO BE USED FOR DESIGN OR CONSTRUCTIC `r �rnnwoa e [spera�r� �Duriil.s, ,- ra• C Legend 2 r �a a� 0 r Cn a� CU 0 06 z a� Q w v a .2 r C d E L V r Q c E L ci fC a� Q Notes Packet Pg. 30 1 2.3.b LOT 35 a , n Site Plan IPERMEABLE II PAVEMENT (TYP.) — I T LOT B LOT B UNDER 6,600 SF'.* SEPARATE PERMIT 5' PRIVATE DRAMIA6E EASamu TD BENEFIT LOT A ,Qoo9 fo,_ T xszr e.a resin w • �—TYPE 1 CB (m) ALLEY PERNEARE PAVEMENT (TM) +®•a•ziw ix..H• 5' BSBL as ar _ OT32 Im � I • I INRLTRATION 7R CN 33' X 5' X 1.5' PROPOSED LOT A I 7,080 SF v• 20' BSB AREAIDRAIN (1YP.) iza • _e'I. 3 a GRAPHIC SCALE 3,0 4 Ir T II SCALE:1" = 30' II k mQ a rusys•ziw zs.4s• I � is ' 94 ,d � zs -PORTION LOT 30 To BE D ICATED TO CITY OFEDMONDS 128 sF f r a Packet Pg. 31 2.4 City Council Agenda Item Meeting Date: 07/13/2021 Presentation of Stormwater Management Code (ECDC 18.30) Update Staff Lead: Zachary Richardson Department: Engineering Preparer: Rob English Background/History Staff Recommendation This item is scheduled for a presentation at the July 20th City Council meeting. Background The City's municipal NPDES permit with the Washington Department of Ecology requires that the City maintain adequate stormwater management code for new development in order to protect surface waters. Each 5-year cycle of the permit requires an update to the City code to remain compliant with the most current guidance from Ecology. The current permit requires that our codes be updated to reflect their 2019 Surface Water Management Manual for Western Washington (SWMMWW) by July of 2022, but staff have proposed to have the new code effective 1/1/2022 for better clarity of application of standards for future projects. Narrative The City must adopt drainage management code which is at least as protective as SWMMWW, but the City does have the ability to add Edmonds -specific provisions which are in addition to Ecology minimums. The difference between SWMMWW and Edmonds codes are managed in the Edmonds Stormwater Addendum (Addendum) so that the update to ECDC 18.30 is ultimately to adopt the 2019 SWMMWW as modified in the Addendum. The revised versions of both ECDC 18.30 and the Addendum are attached in a clean version (as proposed) and a redlined version, which tracked all changes between the current proposal and the existing code. The changes since the previous version of the drainage code are summarized in Attachment E (2022 ECDC 18.30 and Storm water Addendum Summary of Changes) and are broken into three categories. 1. Ecology directed provisions, shown in orange, are revisions need to generally maintain compliance with Ecology guidance. These are generally items that the City does not have the ability to omit or revise in the code. 2. Staff -proposed revisions for clarity only, are shown in white, and generally will not impact development. These revisions are predominantly to assist staff in communicating requirements to designers and to assist with enforcement; they are not new impacts. 3. Staff -proposed revisions which are substantive changes, are shown in green, and would be anticipated to have some potential for impact on development. Packet Pg. 32 2.4 Ecology did a reorganization of the manual for the current version, so there are a fair number of changes to their manual, but most are non -substantive. Most of the updates are reorganizational only and not changes to requirements themselves. See Attachment G and Attachment F for more information on the Ecology revisions. Staff have proposed four substantive changes to the Edmonds -specific portions of code. 1. Changes to the way new connections of existing impervious surfaces are handled; revised to be treated like new impervious and mitigated for in accordance with drainage code. 2. Removed Edmonds Way as 'direct discharge basin' and any corresponding exemptions; project in Edmonds Way to be treated same as rest of City. 3. Increased protections of Perrinville Creek by (a) increasing the application of the City "retro-fit" LID requirement and (b) increasing the flow control standard for projects within the basin. 4. Revising the LID BMP list so that the Edmonds -specific detention BMP is used for LID treatment before the "perforate pipe connection" BMP See the attached documents for more details on the changes and their anticipated impacts. Staff is notifying the City Council of the proposed code changes and requesting comments prior to beginning the permitting and approval process. The approval process will include a SEPA public comment period, and formal public hearing prior to final adoption. Attachments: Attachment A_Revised ECDC 18.30_Clean Attachment B_ECDC 18.30_Redlines Attachment C_Revised Edmonds Stormwater Addendum Clean Attachment D_Edmonds Stormwater Addendum_ Redlines Attachment E_Edmonds Summary of Changes Attachment F_Ecology Summary fo Changes with Edmonds Response Attachment G_Crosswalk_ 2014 - 2019 SWMMWW Attachment H_ECDC 18.30 Update_Draft Presentation Packet Pg. 33 2.4.a Edmonds Chapter 18.30 STORM WATER MANAGEMENT Chapter 18.30 STORMWATER MANAGEMENT Sections: 18.30.000 Purposes. 18.30.010 Definitions. 18.30.020 Authority and Regulation. 18.30.030 Applicability. 18.30.040 Exemptions. 18.30.050 Administration. 18.30.060 Requirements. 18.30.070 Exceptions, Adjustments, and Appeal. 18.30.080 Access and Covenants. 18.30.090 Post Construction Inspection and Maintenance Roles and Responsibilities. 18.30.100 Enforcement Procedures. 18.30.000 Purposes. Page 1/25 A. To set forth standards for managing stormwater runoff from construction and development sites to minimize 1. Degradation of surface water quality by controlling the scouring and sedimentation of creeks, streams, wetlands, ponds, lakes, other water bodies. 2. Degradation of groundwater quality. 3. Damage to adjacent and other downstream private properties from erosion or other impacts from stormwater runoff. 4. Damage of City -owned parcels, City roads, rights -of -way and associated infrastructure. B. To comply with requirements in the Phase II National Pollutant Discharge Elimination System (NPDES) Municipal Stormwater Permit as issued by the Washington State Department of Ecology (Ecology). C. To complement site planning activities that minimize: 1. Impervious surfaces area. 2. The loss of native or non-native site vegetation. 3. The generation of stormwater runoff. D. To make low impact development (LID) the preferred and commonly used approach to site development; to require LID be considered at the site planning stage; and to implement LID BMPs unless they are infeasible. E. To require that all publicly -owned and privately -owned Stormwater Treatment and Flow Control best management practices (BMPs)/Facilities are operated, maintained and repaired in manner that conforms to this chapter. F. To provide the authority for the City to inspect privately -owned Stormwater Treatment and Flow Control BMPs/Facilities. G. To provide enforcement procedures for ensuring compliance with this chapter. Version: June 2021 Packet Pg. 34 2.4.a Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 2/25 18.30.010 Definitions. For the purposes of this chapter, the following definitions shall apply: Arterial. A road or street primarily for through traffic. The term generally includes roads or streets considered collectors. It does not include local access roads which are generally limited to providing access to abutting property. See also RCW 35.78.010, RCW 36.86.070, and RCW 47.05.021. Adjustment. A variation in the application of a minimum requirement to a particular project. Adjustments provide substantially equivalent environmental protection. Applicant. The owning individual(s) or corporations or their representatives applying for the permits or approvals described in this chapter. Approval. The proposed work or completed work conforming to this chapter as approved by the public works Director or their designee. Best management practices (BMPs). The schedules of activities, prohibitions of practices, maintenance procedures, and structural and/or managerial practices approved by the City that, when used singly or in combination, prevent or reduce the release of pollutants and other adverse impacts to waters of Washington State. Bioretention BMPs. Engineered facilities that treat stormwater by passing it through a specified soil profile, and either retain or detain the treated stormwater for flow attenuation. Refer to the 2019 Stormwater Management Manual for Western Washington (SWMMWW), Volume V for bioretention BMP types and design specifications. Category 1 Project Site. A project site subject to Minimum Requirements No.I through No.5. See ECDC 18.30.60. C. Category 2 Project Site. A project site subject to Minimum Requirements No.1 through No.9. See ECDC 18.30.60.C. Certified Erosion and Sediment Control Lead (CESCL). An individual who has current certification through an approved erosion and sediment control training program that meets the minimum training standards established by Ecology (see BMP C160 in the SWMMWW). A CESCL is knowledgeable in the principles and practices of erosion and sediment control. The CESCL must have the skills to assess site conditions and construction activities that could impact the quality of stormwater and, the effectiveness of erosion and sediment control measures used to control the quality of stormwater discharges. Certification is obtained through an Ecology approved erosion and sediment control course. Course listings are provided online at Ecology's website. City's municipal separate storm sewer system or "MS4." A conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, manmade channels, or storm drains) that are owned or operated by the City of Edmonds, designed or used for collecting or conveying stormwater, and are not a combined sewer nor part of a publicly owned treatment works as defined in 40 Code of Federal Regulations (CFR) 122.2, and which is defined as "large" or "medium" or "small" or otherwise designated by Ecology pursuant to 40 CFR 122.26. Clearing. The destruction and removal of vegetation by manual, mechanical, or chemical methods. Commercial Agriculture. Those activities conducted on lands defined in RCW 84.34.020(2) and activities involved in the production of crops or livestock for commercial trade. An activity ceases to be considered commercial agriculture when the area on which it is conducted is proposed for conversion to a nonagricultural use or has lain idle for more than five years, unless the idle land is registered in a federal or state soils conservation program, or unless the activity is maintenance of irrigation ditches, laterals, canals, or drainage ditches related to an existing and ongoing agricultural activity. Common plan of development or sale. A site where multiple separate and distinct construction activities may be taking place at different times on different schedules and/or by different contractors, but still under a single plan. Examples include: 1) phase projects and projects with multiple filings or lots, even if the separate phases or Version: June 2021 Packet Pg. 35 2.4.a Edmonds Page 3/25 Chapter 18.30 STORM WATER MANAGEMENT filings/lots will be constructed under separate contract or by separate owners (e.g., a development where lots are sold to separate builders); 2) a development plan that may be phased over multiple years, but is still under a consistent plan for long-term development; 3) projects in a contiguous area that may be unrelated but still under the same contract, such as construction of a building extension and a new parking lot at the same facility; and 4) linear projects such as roads, pipelines, or utilities. If the project is part of a common plan of development or sale, the disturbed area of the entire plan must be used in determine permit requirements. Converted vegetation (areas). The change in land cover changed from native vegetation, pasture scrub/shrub, or unmaintained non-native vegetation to lawn or landscaped areas, or where native vegetation is converted to pasture. Creek. Is synonymous with "streams," which is defined in ECDC 23.40.320. Detention facility. An above or below ground facility, such as a pond or tank, that temporarily stores stormwater runoff and subsequently releases it at a slower rate than it is collected by the drainage facility system. There is little or no infiltration of stored stormwater. Development. Land -disturbing activities, including Class IV general forest practices that are conversions from timber land to other uses. Creation or addition of hard surfaces, or replacement of hard surface that is not part of a routine maintenance activity. Structural development, including construction, installation, replacement, or expansion of a building or other structure. Subdivision, short subdivision, and binding site plans, as defined and applied in Chapter 58.17 RCW Director. The City's Public Works and Utilities Director or a designee with an appropriate background in engineering or another related discipline. Discharge point. The location where a discharge leaves the municipal separate storm sewer system (MS4) through the City's MS4 facilitiesBMPs designed to infiltrate. Ecology. The Washington State Department of Ecology Effective impervious surface. Those impervious surfaces that are connected via sheet flow or discrete conveyance to a drainage system. Impervious surfaces on residential development sites are considered ineffective if. 1) the runoff is dispersed through at least 100 feet of native vegetation in accordance with BMP T5.30 — "Full Dispersion," as described in Chapter 5 of Volume V of the SWMMWW; 2) residential roof runoff is infiltrated in accordance with downspout Full Infiltration Systems in BMP T5.10A in Volume III of the SWMMWW; or 3) approved continuous runoff modeling methods indicate the entire runoff file is infiltrated. Erodible or leachable materials. Wastes, chemicals, or other substances that measurably alter the physical or chemical characteristics of runoff when exposed to rainfall. Examples include erodible soils that are stockpiled, uncovered process wastes, manure, fertilizers, oily substances, ashes, kiln dust, and garbage dumpster leakage. Erosion. The wearing away of the land surface by running water, wind, ice, or other geological agents, including such processes as gravitational creep. Also, detachment and movement of soil or rock fragments by water, wind, ice, or gravity. See the SWMMWW Glossary for examples of types of water erosion. Excavation. The mechanical removal of earth material. Exception. Relief from the application of a minimum requirement to a project. Fill. A deposit of earth material placed by artificial means. Groundwater. Water in a saturated zone or stratum beneath the land surface or below a water body Hard surface. An impervious surface, a permeable pavement, or a vegetated roof. Version: June 2021 Packet Pg. 36 2.4.a Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 4/25 Highway. A main public road connecting towns and cities. In Edmonds, this includes State Route 99, State Route 524, and portions of State Route 104, that are classified as principal arterials in the City's comprehensive transportation plan. Illicit discharge. Any direct or indirect non-stormwater discharge to the City's MS4, groundwaters, or a water body, except as expressly allowed by ECDC Chapter 7.200. Impervious surface. A non -vegetated surface area that either prevents or retards the entry of water into the soil mantle as under natural conditions prior to development. A non -vegetated surface area which causes water to run off the surface in greater quantities or at an increased rate of flow from the flow present under natural conditions prior to development. Common impervious surfaces include, but are not limited to, roof tops, walkways, patios, driveways, parking lots or storage areas, concrete or asphalt paving, gravel roads, packed earthen materials, and oiled, macadam or other surfaces that similarly impede the natural infiltration of stormwater. Open, uncovered retention/detention facilities shall not be considered impervious surfaces for purposes of determining whether the thresholds for application of minimum requirements are exceeded. Open, uncovered retention/detention facilities shall be considered impervious surfaces for purposes of runoff modeling. Outdoor swimming pools shall be considered impervious surfaces in all situations. In addition, lawns, landscaping, sports fields, golf courses, and other areas that have modified runoff characteristics resulting from the addition of underdrains and impermeable or low permeability liners are to be considered impervious surfaces. If no liner is installed, these areas (lawns, landscaping, sports fields, golf courses, etc.) served by underdrains may be considered partially pervious if the underdrain is set a minimum of 8 inches above the in -situ soils in a manner to allow infiltration over the facility bottom. Lake. An inland body of fresh water surrounded by land. Land disturbing activity. Any activity that results in a change in the existing soil cover (both vegetative and non - vegetative) and/or the existing soil topography. Land -disturbing activities include but are not limited to demolition, clearing, grading, filling, and excavation. Compaction that is associated with stabilization of structures and road construction shall also be considered a land -disturbing activity. Vegetation maintenance practices, including landscape maintenance and gardening, are not considered land -disturbing activity. Stormwater facility maintenance is not considered land disturbing activity if conducted according to established standards and procedures. Low impact development (LID). A stormwater and land use strategy that strives to mimic pre -disturbance hydrologic processes of infiltration, filtration, storage, evaporation and transpiration by emphasizing conservation, use of on -site features, site planning, and distributed stormwater management practices that are integrated into a project design. LID Best Management Practices (BMPs). Distributed stormwater management practices, integrated into a project design, that emphasize pre -disturbance hydrologic processes of infiltration, filtration, storage, evaporation and transpiration. LID BMPs include, but are not limited to, bioretention, rain gardens, permeable pavements, roof downspout controls, dispersion, soil quality and depth, minimal excavation foundations, vegetated roofs, and water re -use. LID principles. Land use management strategies that emphasize conservation, use of on -site natural features, and site planning to minimize impervious surfaces, native vegetation loss, and stormwater runoff. Maintenance. Repair and maintenance activities conducted on currently serviceable structures, facilities, and equipment that involves no expansion or use beyond that previously existing and results in no significant adverse hydrologic impact. It includes those usual activities taken to prevent a decline, lapse, or cessation in the use of structures and systems. Those usual activities may include replacement of dysfunctional facilities, including cases where environmental permits require replacing an existing structure with a different type structure, as long as the functioning characteristics of the original structure are not changed. One example is the replacement of a collapsed, fish blocking, round culvert with a new box culvert under the same span, or width, of roadway. In regard to stormwater facilities, maintenance includes assessment to ensure ongoing proper operation, removal of built up pollutants (i.e., sediments), replacement of failed or failing treatment media, and other actions taken to correct defects as identified in the maintenance standards of Appendix A, Volume V of the SWMMWW. Version: June 2021 Packet Pg. 37 2.4.a Edmonds Page 5/25 Chapter 18.30 STORM WATER MANAGEMENT Maximum extent practicable (MEP). Refers to paragraph 402(p)(3)(B)(iii) of the federal Clean Water Act which reads as follows: Permits for discharges from municipal storm sewers shall require controls to reduce the discharge of pollutants to the maximum extent practicable, including management practices, control techniques, and system, design, and engineering methods, and other such provisions as the Administrator or the State determines appropriate for the control of such pollutants. MS4. The City's municipal separate storm sewer system. Native vegetation. Vegetation comprised of plant species, other than noxious weeds, indigenous to the coastal region of the Pacific Northwest which could have been reasonably expected to occur naturally on the site. Examples include trees such as Douglas fir, western hemlock, western red cedar, alder, big -leaf maple, and vine maple; shrubs such as willow, elderberry, salmonberry, and salal; and herbaceous plants such as sword fern, foam flower, and fireweed. Natural drainage systems and outfalls. The location of the channels, swales, and other non -manmade conveyance systems as defined by the earliest documented topographic contours existing for the subject property, either from maps or photographs, or such other means as appropriate. New Development. Land disturbing activities, including Class IV -general forest practices that are conversions from timberland to other uses; structural development, including construction or installation of a building or other structure; creation of hard surfaces; and subdivision, short subdivision, and binding site plans, as defined and applied in Chapter 58.17 RCW. ECDC 18.30 does not distinguish the difference between new development and redevelopment; all projects in Edmonds shall meet the requirements for new development. New Impervious Surface. A surface that is: 1) changed from a pervious surface to an impervious surface (e.g., resurfacing by upgrading from dirt to gravel, a bituminous surface treatment ("chip seal"), asphalt, concrete, or an impervious structure); or 2) upgraded from gravel to chip seal, asphalt, concrete, or an impervious structure; or 3) upgraded from chip seal to asphalt, concrete, or an impervious structure. Note that if asphalt or concrete has been overlaid by a chip seal, the existing condition should be considered as asphalt or concrete. Outfall. A point source as defined by 40 CFR 122.2 at the point where a discharge leaves the City's MS4 and enters a surface receiving waterbody or surface receiving waters. Outfall does not include pipes, tunnels, or other conveyances which connect segments of the same stream or other surface waters and are used to convey primarily surface waters (i.e., culverts). On -site Stormwater Management BMPs. A synonym for Low Impact Development BMPs. Permeable pavement. Pervious concrete, porous asphalt, permeable pavers or other forms of pervious or porous paving material intended to allow passage of water through the pavement section. It often includes an aggregate base that provides structural support and acts as a stormwater reservoir. Pervious Surface. Any surface material that allows stormwater to infiltrate into the ground. Examples include lawn, landscape, pasture, native vegetation areas, and permeable pavements. Person. Any individual, partnership, corporation, association, organization, cooperative, public or municipal corporation, agency of the state, or City government unit, however designated. Pollution -generating hard surface (PGHS). Those hard surfaces considered to be a significant source of pollutants in stormwater runoff. See the listing of surfaces under pollution -generating impervious surface. Pollution -generating impervious surface (PGIS). Those impervious surfaces considered to be a significant source of pollutants in stormwater runoff. Such surfaces include those which are subject to: vehicular use; industrial activities (as further defined in the glossary of the SWMMWW); storage of erodible or leachable materials, wastes, or chemicals, and which receive direct rainfall or the run-on or blow-in of rainfall; metal roofs unless they are coated with an inert, non -leachable material (e.g., baked -on enamel coating); or roofs that are subject to venting significant amounts of dusts, mists, or fumes from manufacturing, commercial, or other indoor activities. Version: June 2021 Packet Pg. 38 2.4.a Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 6/25 Pollution -generating pervious surfaces (PGPS). Any pervious surface subject to 1) vehicular use, 2) industrial activities (as further defined in the glossary of the SWMMWW); or 3) storage of erodible or leachable materials, wastes, or chemicals, and that receive direct rainfall or run-on or blow-in of rainfall, 4) use of pesticides and fertilizers, or 5) loss of soil. Typical PGPS include permeable pavement subject to vehicular use, lawns, and landscaped areas including: golf courses, parks, cemeteries, and sports fields (natural and artificial turf). Pre -developed condition. The native vegetation and soils that existed at a site prior to the influence of Euro- American settlement. The pre -developed condition shall be assumed to be a forested land cover unless reasonable, historic information is provided that indicates the site was prairie prior to settlement. Project: Any proposed action to alter or develop a site. Project site. That portion of a property, properties, and/or right-of-way subject to land -disturbing activities, new hard surfaces, or replaced hard surfaces. For projects that involve land disturbing activity on one or more parcels and/or land disturbing activity in the City right-of-way, the "Project site" includes all areas of land disturbance. If the project is part of a common development plan or sale, the disturbed area of the entire plan shall be used in determining permit requirements. Rain garden. A non -engineered shallow landscaped depression, with compost -amended native soils and adapted plants. The depression is designed to pond and temporarily store stormwater runoff from adjacent areas, and to allow stormwater to pass through the amended soil profile. Receiving waterbody or Receiving waters. Naturally and/or reconstructed naturally occurring surface water bodies, such as creeks, streams, rivers, lakes, wetlands, estuaries, and marine waters, or groundwater, to which a MS4 discharges. Redevelopment. ECDC 18.30 does not distinguish the difference between new development and redevelopment; all projects in Edmonds shall meet the requirements for new development. Where existing unmitigated surfaces are to remain, the additional "retro-fit" requirement per ECDC 18.30.060.D.5.b.i Replaced hard surface. For structures means the removal and replacement of hard surfaces down to the foundation. For other hard surfaces, it means the removal down to bare soil or base course and replacement. Replaced impervious surface. For structures, the removal and replacement of any exterior impervious surfaces down to the foundation. For other impervious surfaces, it means the removal down to bare soil or base course and replacement. Roadway. Traveled hard surface portion of any public or private road or street. Road -related project. A project that all of, or the majority of, the new or replaced hard surface consist of roadway, shoulders, curbs, gutters, sidewalks, or walkways, either publicly or privately funded. Frontage improvements constructed as a requirement for a development project are not consider a road -roadway project. Runoff. Water originating from rainfall and other precipitation that is found in drainage facilities, rivers, streams, springs, seeps, ponds, lakes and wetlands, as well as shallow ground water. It also means the portion of rainfall or other precipitation that becomes surface flow and interflow. Site. The area defined by the legal boundaries of a parcel or parcels of land that is (are) subject to development. For road projects, or utility projects in the right-of-way, the length of the project site and the right-of-way boundaries define the site. Note that drainage impacts are generally assessed for the "project site", under separate definition. Slope. The degree of deviation of a surface from the horizontal; measured as a numerical ratio, percent, or in degrees. Expressed as a ratio, the first number is the horizontal distance (run) and the second is the vertical distance (rise), as 2:1. A 2:1 slope is a 50 percent slope. Expressed in degrees, the slope is the angle from the horizontal plane, with a 90-degree slope being vertical (maximum) and 45 degrees being a 1:1 or 100 percent slope. Version: June 2021 Packet Pg. 39 2.4.a Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 7/25 Soil. The unconsolidated mineral and organic material on the intermediate surface of the earth that serves as a natural medium for the growth of land plants. Source control BMPs. A structure or operation that is intended to prevent pollutants from coming into contact with storm water through physical separation of areas or careful management of activities that are sources of pollutants. The SWMMWW separates source control BMPs into two types. Structural source control BMPs are physical, structural, or mechanical devices, or facilities that are intended to prevent pollutants from entering stormwater. Operational Source Control BMPs are non-structural practices that prevent or reduce pollutants from entering stormwater. See Volume IV of the SWMMWW for details. Stormwater facility. A constructed component of a stormwater drainage system, designed and constructed to perform a particular function or multiple functions. Stormwater facilities include, but are not limited to, pipes, swales, ditches, culverts, street gutters, detention ponds, retention ponds, constructed wetlands, infiltration devices, catch basins, oil/water separators, and biofiltration swales. Stormwater Management Manual for Western Washington (SWMMWW). The Washington State Department of Ecology's 2019Stormwater Management Manual for Western Washington. Referred to as the 2019 SWMMWW Stormwater site plan. The comprehensive report containing all of the technical information and analysis necessary for regulatory agencies to evaluate a proposed development project for compliance with stormwater requirements. Contents of the Stormwater Site Plan will vary with the type and size of the project, and individual site characteristics. It includes a Construction Stormwater Pollution Prevention Plan (Construction SWPPP) and a Permanent Stormwater Control Plan (PSC Plan). Guidance on preparing a Stormwater Site Plan is contained in Chapter 3 of Volume I of the SWMMWW. Stormwater Treatment and Flow Control BMPs/Facilities. Detention facilities, treatment BMPs/facilities, bioretention, vegetated roofs, and permeable pavements that help meet Minimum Requirements No.6 (Treatment), Minimum Requirement No.7 (Flow Control), or both as described in ECDC 18.30.060. Threshold discharge area. An area within a project site draining to a single natural discharge location or multiple natural discharge locations that combine within one -quarter mile downstream (as determined by the shortest flowpath). The examples in Figure 1: Example TDA Delineations below,illustrate this definition. The purpose of this definition is to clarify how the thresholds of this code are applied to project sites with multiple discharge points Version: June 2021 Packet Pg. 40 Edmonds Chapter 18.30 STORM WATER MANAGEMENT Figure 1: Example TDA Delineations 2.4.a Page 8/25 Example of a Project Site Example of a Project Site Example of a Project Site with with a single natural with multiple natural multiple natural discharges and discharge and a single TDA discharges and a single TDA multiple TDAs ' .._.�'--- Jy ,TDA - TDA Single - TDA 2 Natural r Natural J 1 Natural discharge Greater than location discharge discharge 1I4 mile locations 114 milelocations r ` 114 miles f 1/4 mile i i Example of a road project with multiple d1wharge points and a single TDA o mBecause the right -most discharge . connecls to the other two discharge flow �I roadway crown paths within I mite, all areas are �i connected as one TDA. Discharge 114 mde 114 mile location — - 114 mile -. c S 3 / Example of a road project with multiple ` / discharge points and multiple TDAs. �1 Note: Shaded areas represent - Discharge 11+i mle the limits of the location project site. 11 4 NOT TO SCALE Example TDA Delineations DEPARTMENT OF Revised March 2018 ECOLOGYPlease see http.IA+vwwecyy wa.govIoopyright htmf for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. Version: June 2021 Packet Pg. 41 2.4.a Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 9/25 Vehicular Use. Regular use of an impervious or pervious surface by motor vehicles. The following are subject to regular vehicular use: roads, un-vegetated road shoulders, bike lanes within the traveled lane of a roadway, driveways, parking lots, unrestricted access fire lanes, vehicular equipment storage yards, and airport runways. The following are not considered subject to regular vehicular use: sidewalks not subject to drainage from roads for motor vehicles, paved bicycle pathways separated from and not subject to drainage from roads for motor vehicles, restricted access fire lanes, and infrequently used maintenance access roads. Waterbody. Surface waters including rivers, streams, lakes, marine waters, estuaries, and wetlands. Waters of the state. Includes those waters defined as "waters of the United States" in 40 CFR Subpart 122.2 within the geographic boundaries of Washington State, and "waters of the state" as defined in Chapter 90.48 RCW which includes lakes, rivers, ponds, streams, inland waters, underground waters, salt waters and all other surface waters and water courses within the jurisdiction of the state of Washington. Wetlands. As defined in ECDC 23.40.005. [Ord. 4026 § 1 (Att. A), 2016]. 18.30.020 Authority and Regulation. A. The Public Works and Utilities Director shall administer this chapter and shall be referred to as the Director. B. The Director shall have the authority to develop, implement, and enforce policies and procedures to administer and enforce this chapter per ECDC 18.30.110 and 18.30.120, such as the Edmonds Stormwater Addendum. C. The requirements of this chapter are minimum requirements. They do not replace, repeal, abrogate, supersede, or affect any other more stringent requirements, rules, regulations, covenants, standards, or restrictions. Where this chapter imposes requirements that are more protective of human health or the environment than those set forth elsewhere, the provisions of this chapter shall prevail. When this chapter imposes requirements that are less protective of human health or the environment than those set forth elsewhere, the provisions of the more protective requirements shall prevail. D. The Director shall have the authority to impose additional requirements on a project or site to meet the purpose of this chapter based on site -specific factors including, but not limited to, location, soil conditions, slope, and designated use. E. Approvals and permits granted under this chapter are not waivers of the requirements of any other laws, nor do they indicate compliance with any other laws. Compliance is still required with all applicable federal, state and local laws and regulations, including rules promulgated under authority of this chapter. F. Compliance with the provisions of this chapter does not necessarily mitigate all impacts to the environment. Thus, compliance with this chapter should not be construed as mitigating all drainage water or other environmental impacts, and additional mitigation may be required to protect the environment pursuant to other applicable laws and regulations. The primary obligation for compliance with this chapter and for preventing environmental harm on or from property is placed upon the applicant. [Ord. 3792 § 1, 2010]. 18.30.030 Applicability. A. This chapter applies to applications: 1. Submitted on or after January 1, 2022, and 2. Submitted prior to January 1, 2017, which have not started construction by January 1, 2022, and 3. Submitted prior to January 1, 2022, which have not started construction by July 1, 2027. Version: June 2021 Packet Pg. 42 Edmonds Page 10/25 Chapter 18.30 STORM WATER MANAGEMENT B. This chapter applies to the following actions on sites that discharge to the City's MS4 or discharges to waters of the state whether or not a City -issued permit is required: 1. Land -disturbing activity, or 2. Creation of new hard surfaces, or 3. Replacement of existing hard surfaces, or 4. Conversion of pervious surfaces, or 5. New connections to the City's MS4, or 6. Any other actions that can increase the volume or rate of stormwater runoff, or cause the generation of pollutants, from the site. 18.30.040 Exemptions. A. Full Exemptions. The following land uses and land -disturbing activities are exempt from the provisions of this chapter: 1. Forest practices regulated under WAC Title 222, except for Class IV general forest practices that are conversions from timberland to other uses, are exempt from the provisions of the minimum requirements. 2. Commercial agriculture practices that involve working land for production are generally exempt. However, land conversion from timberland to agriculture and the construction of impervious surfaces are not exempt. 3. Construction of drilling sites, waste management pits, and associated access roads, and construction of transportation and treatment infrastructure such as pipelines, natural gas treatment plants, natural gas pipeline compressor stations, and crude oil pumping stations are exempt. Operators are encouraged to implement and maintain best management practices to minimize erosion and control sediment during and after construction activities to help ensure protection of surface water quality during storm events. 4. The following pavement maintenance practices or activities are exempt: pothole and square -cut patching, overlaying existing asphalt or concrete pavement with asphalt or concrete without expanding the area of coverage, shoulder grading, reshaping/regrading drainage systems, crack sealing, resurfacing with in -kind material without expanding the road prism, pavement preservation activities that do not expand the road prism, and vegetation maintenance. B. Partial Exemptions. The following land uses and land -disturbing activities are partially exempt from the provisions of this chapter: 1. Underground utility projects that replace the ground surface with in -kind material or materials with similar runoff characteristics are only subject to Minimum Requirement No. 2, Construction Stormwater Pollution Prevention. a. Utility instillation as part of a development project, whether in the right-of-way or on private property, are not considered an underground utility project for the sake of this partial exemption. 2. The following pavement maintenance practices or activities are considered development, and therefore are not categorically exempt. a. Removing and replacing a paved surface to base course or a lower level, or repairing the pavement base: These are considered replaced hard surfaces. Version: June 2021 Packet Pg. 43 Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 11/25 b. Extending the pavement edge without increasing the size of the road prism or paving graveled shoulders: these are considered new hard surfaces. c. Resurfacing by upgrading from dirt to gravel, asphalt, or concrete; or upgrading from gravel to asphalt or concrete; or upgrading from a bituminous surface treatment ("chip seal") to asphalt or concrete: these are considered new hard surfaces. 18.30.050 Administration. A. Application, Submittals, and Review. 1. The Director shall review all plans and all other submittals required by ECDC 18.30.050.A.3 for compliance with this chapter when: a. An application for a City permit is required under all other chapters of ECDC Title 18 or 19, or b. A subdivision application is submitted per ECDC 20.75.040. 2. In all other situations when actions under ECDC 18.30.030 apply to a project site, review shall be under a Stormwater permit. 3. All stormwater review submittals shall contain, in addition to the information required under any other applicable City code, a Stormwater Site Plan as described in the Edmonds Stormwater Addendum (see ECDC 18.30.060) and any other information required by the Director. B. Inspections. 1. The Director shall inspect projects at various stages of the work to determine if they comply with the requirements of this chapter, and enforcement actions shall be taken as necessary. These inspections will include, but not be limited to, the following: a. Prior to site clearing and construction to assess site erosion potential, and b. During construction to verify proper installation and maintenance of required erosion and sediment controls and other approved plan components, and c. All permanent stormwater treatment and flow control BMPs/facilities and catch basins in new residential developments every six months until 90 percent of the lots are constructed (or when construction is stopped and the site is fully stabilized) to identify maintenance needs and enforce compliance with maintenance standards as needed, and d. Upon completion of construction and prior to final approval to ensure proper installation of permanent Stormwater control facilities and verify that a maintenance plan is completed and responsibility for maintenance is assigned for stormwater treatment and flow control BMPs/facilities, and e. Post -Construction inspections per ECDC 18.30.090. 2. When reasonably required by the Director to accomplish the purpose of this chapter or to comply with local, state or federal law or regulation on stormwater, special inspection or testing shall be performed by the applicant. C. Fees. Application, review and inspection fees as set in ECDC Chapter 15.00 shall be paid. Version: June 2021 Packet Pg. 44 Edmonds Chapter 18.30 STORM WATER MANAGEMENT 18.30.060 Requirements. Page 12/25 A. Documents. The sources of the stormwater management requirements for the City are from the following documents: 1. Western Washington Phase II Municipal Stormwater Permit, Appendix 1, modification date August 1, 2019 2. 2019 Stormwater Management Manual for Western Washington (SWMMWW) 3. The Edmonds Stormwater Addendum In the event of conflicts between the various provisions, the more stringent provision shall apply. B. Illicit Discharges and Connections. Non-stormwater illicit discharges, including spills, into the MS4, groundwaters, or a water body from any developed or undeveloped lands are prohibited per ECDC Chapter 7.200. C. Thresholds and Applicability 1. The thresholds outlined in this section are only applicable to ECDC 18.30.060.C. See also the Edmonds Stormwater Addendum for supplemental information on thresholds. a. All development shall be required to comply with Minimum Requirement No. 2. b. Category 1 project sites shall comply with Minimum Requirements No. 1 through No. 5. Category 1 includes projects that: i. Result in 2,000 square feet, or greater, of new plus replaced hard surface area, or ii. Have land disturbing activity of 7,000 square feet or greater. c. Category 2 project sites shall comply with Minimum Requirements No. 1 through No. 9. Category 2 includes projects that: i. Result in 5,000 square feet, or greater, of new plus replaced hard surface area, or ii. Convert 0.75 acres, or more, of vegetation to lawn or landscaped areas, or iii. Convert 2.5 acres, or more, of native vegetation to pasture. 2. Additional Requirements for road -related projects. For road -related projects, runoff from the new and replaced hard surfaces (including pavement, shoulders, curbs, and sidewalks) and the converted vegetation areas shall meet all the minimum requirements only if the new hard surfaces total 5,000 square feet or more and total 50 percent or more of the existing hard surfaces within the project limits. Otherwise, the minimum requirements only apply to the new hard surfaces and the converted vegetation areas that exceed the thresholds in (1) above. The project limits shall be defined by the length of the project and the width of the right-of-way. 3. New Connections to the City's MS4 when the proposed connection does not involve activity that meets the definition of development. Sites that are not currently connected to the City's MS4 but that wish to connect directly or indirectly to the City's MS4 may be allowed on a case -by -case basis, subject to City approval. For sites that propose to drain greater than or equal to 2,000 square feet of hard surface area to the City's MS4, the project shall comply with the requirement of this chapter, treating all hard surfaces to be drained to the City system as new hard surfaces, unless applicant can demonstrate that the site will discharge in the same manner and quantities prior to the proposed project. Applicant shall account for natural dispersion and/or infiltration which may be occurring if these new hard surfaces area currently drain through pervious areas. 4. Minimum Requirements may be met for an equivalent (flow and pollution characteristics) area. The equivalent area may be within the same TDA. If the equivalent area is outside the TDA, or off -site, the equivalent area must drain to the same receiving water and the guidance for equivalent facilities using in - basin transfers must be followed, as detailed in Appendix D of Volume 1 of SWMMWW. Version: June 2021 Packet Pg. 45 Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 13/25 D. Minimum Technical Requirements. This section describes the minimum technical requirements for stormwater management at development sites. 1. Minimum Requirement No. 1 — Preparation of Stormwater Site Plans The City shall require a Stormwater Site Plan from all projects meeting the thresholds in ECDC 18.30.060.C. Stormwater Site Plans shall use site -appropriate development principles to retain native vegetation and minimize impervious surfaces to the extent feasible. Stormwater Site Plans shall be prepared in accordance with Chapter 3 of Volume 1 of the SWMMWW and the requirements in the Edmonds Stormwater Addendum. 2. Minimum Requirement No. 2 — Construction Stormwater Pollution Prevention Plan (SWPPP) a. Thresholds: i. All development projects are responsible for preventing erosion and discharge of sediment and other pollutants into receiving waters. Compliance with this minimum requirement can be achieved for an individual site if the site is covered under Ecology's General NPDES Permit for Stormwater Discharges Associated with Construction Activities and fully implementing the requirements of that permit. ii. A Construction SWPPP is required for all projects which a) result in 2,000 square feet or more of new plus replaced hard surface area, b) where a structure with an exterior hard surface area of at least 2,000 square feet is being demolished, c) which disturb 7,000 square feet or more of land, or d) when the site falls within the Earth Subsidence Landslide Hazard Area, Landslide Hazard Area or steep slope critical area. Projects that do not meet any of the above criteria are not required to prepare a Construction SWPPP, but must consider all of the elements listed below for Construction SWPPPs and develop controls for all Construction SWPPP elements that pertain to the project site. b. General Requirements: i. The SWPPP shall include a narrative and drawings. All BMPs shall be clearly referenced in . the narrative and marked on the drawings. The SWPPP narrative shall include documentation to explain and justify the pollution prevention decisions made for the project. Each of the thirteen elements referenced below must be considered and included in the SWPPP unless site conditions render the element unnecessary and the exemption from that element is clearly justified in the narrative of the SWPPP. ii. Clearing and grading activities for developments shall be permitted only if conducted pursuant to an approved site development plan (e.g., building permit, subdivision approval) that establishes permitted areas of clearing, grading, cutting, and filling. These permitted clearing and grading areas and any other areas required to preserve critical or sensitive areas, buffers, native growth protection easements, or tree retention areas as required by the City, shall be delineated on the site plans and the development site. iii. The SWPPP shall be implemented beginning with initial land disturbance and until final stabilization. Sediment and Erosion control BMPs shall be consistent with the BMPs contained in Chapter 4 of Volume II of the SWMMWW. c. Seasonal Work Limitations: From October 1 through April 30, clearing, grading, and other soil disturbing activities may only be authorized by the City if it can be demonstrated that silt -laden runoff will be prevented from leaving the site through a combination of the following: Version: June 2021 Packet Pg. 46 Edmonds Page 14/25 Chapter 18.30 STORM WATER MANAGEMENT i. Site conditions including existing vegetative coverage, slope, soil type, and proximity to receiving waters; and ii. Limitations on activities and the extent of disturbed areas; and iii. Proposed erosion and sediment control measures, in accordance with ECDC 18.30.060.D.2.d below. Based on the information provided and/or local weather conditions, the City may expand or restrict the seasonal limitation on site disturbance. The following activities are exempt from the seasonal clearing and grading limitations, except for sites lying in whole or in part within an earth subsidence and landslide hazard area as defined by ECDC 19.10.020.F: Routine maintenance and necessary repair of erosion and sediment control BMPs, ii. Routine maintenance of public facilities or existing utility structures that do not expose the soil or result in the removal of the vegetative cover to soil, and iii. Activities where there is one hundred percent infiltration of surface water runoff within the site in approved and installed erosion and sediment control facilities. d. Construction SWPPP Elements Construction SWPPP elements are required in accordance with Chapter 3, Section 3.4.2 of Volume I of the SWMMWW and the requirements in the Edmonds Stormwater Addendum 3. Minimum Requirement No. 3 — Source Control of Pollution All known, available and reasonable source control BMPs must be required for all projects approved by the City. Source control BMPs must be selected, designed, and maintained in accordance with Volume IV of the SWMMWW. All single family residential projects shall, at a minimum, incorporate required BMPs from SWMMWW Volume IV, S411 — BMPs for Landscaping and Lawn/Vegetation Management. 4. Minimum Requirement No. 4 — Preservation of Natural Drainage Systems and Outfalls Natural drainage patterns shall be maintained, and discharges from the project site shall occur at the natural location, to the maximum extent practicable. The manner by which runoff is discharged from the project site must not cause a significant adverse impact to downstream receiving waters and down gradient properties. The discharge must have an identified overflow route that is safe and certain, and leads to the ultimate outfall location (such as a receiving water or municipal drainage system). All outfalls require energy dissipation. To demonstrate compliance with this core requirement, all projects shall submit an off -site qualitative analysis. If an existing problem (or potential future problem after development) is identified, mitigation will be required to prevent worsening of that problem. A quantitative analysis may be required for any project deemed to need additional information or where the project proponent or the City determines that a quantitative analysis is necessary to evaluate the off -site impacts or the capacity of the conveyance system. See the Edmonds Stormwater Addendum for additional details on complying with this requirement. 5. Minimum Requirement No. 5 — On -site Stormwater Management a. Applicability: On -site Stormwater Management BMPs are required in accordance with the following project thresholds, standards, and lists to infiltrate, disperse, and retain stormwater runoff on -site to the extent feasible without causing flooding or erosion impacts. See the SWMMWW and the Edmonds Stormwater Addendum for additional details on On -site Stormwater Management BMP infeasibility. Version: June 2021 Packet Pg. 47 Edmonds Chapter 18.30 STORM WATER MANAGEMENT b. Project Thresholds: Page 15/25 There are five project scenarios outlined below that determine the applicability of Minimum Requirement No. 5 — On -site Stormwater Management. The first four scenarios apply to projects that discharge directly or indirectly to the City's MS4. The fifth scenario applies to project discharges that do not enter the City's MS4. Note that more than one of the five scenarios may apply to a given proj ect: Retrofit. Projects that discharge directly or indirectly to the City's MS4 and that contain existing hard surfaces on the parcel or common plan of development that do not drain to an approved stormwater management facility are required to provide On -site Stormwater Management BMPs to manage a portion of those existing hard surfaces that will remain after project completion. BMPs from List No.1 (See ECDC 18.30.060.D.5.d) shall be applied to a minimum of 25 percent of those existing unmanaged surfaces, but to no more than the area equal to the proposed new plus replaced hard surfaces. Within the Perrinville Creek basin, the retrofit value shall be increased from 25% to 50%. Only for those existing unmanaged hard surfaces that remain after project completion, applicants are not required to evaluate BMPs in priority order or document infeasibility for these existing surfaces (as is required under ECDC 18.30.060.D.5.b [ii] and [iii] below). However, if it is determined that the minimum percentage requirement cannot be met due to BMP infeasibility, documentation of BMP infeasibility is required. In addition, when runoff from unmanaged hard surfaces is mixed with runoff from managed hard surfaces, those BMPs must be selected and designed for all areas which contribute runoff to the BMP (per sections [ii] and [iii] below). See the SWMMWW and the Edmonds Stormwater Addendum for additional details on On -site Stormwater Management BMP infeasibility. ii. This requirement is specific to minimum requirement #5 only. The surfaces treated by this requirement do no need to be added to project thresholds or mitigated under other minimum requirements. Impervious surfaces disturbed solely for installation of BMPs proposed to satisfy this requirement need not be consider as replaced hard surfaces for the project. Category 1. Category 1 project sites that discharge directly or indirectly to the City's MS4 and are required to comply with Minimum Requirements No. 1 through No. 5 (per ECDC 18.30.060.C) shall either: a. Use On -site Stormwater Management BMPs from List No.l for all new plus replaced hard surfaces and land disturbed (See ECDC 18.30.060.D.5.d); or b. Demonstrate compliance with the LID Performance Standard (See ECDC 18.30.060.D.5.c). Projects selecting this option cannot use rain gardens. They may choose to use bioretention BMPs as described in the SWMMWW. iii. Category 2. Category 2 project sites that discharge directly or indirectly to the City's MS4 and are required to comply with Minimum Requirements No. 1 through No. 9 (per ECDC 18.30.060.C) shall either: a. Use On -site Stormwater Management BMPs from List No.2 for all new plus replaced hard surfaces and land disturbed (See ECDC 18.30.060.D.5.e); or b. Demonstrate compliance with the LID Performance Standard (See ECDC 18.30.060.D.5.c). Projects selecting this option cannot use rain gardens. They may choose to use bioretention BMPs as described in the SWMMWW. iv. Direct Discharge Requirement. Projects that discharge directly to Puget Sound through the City's MS4 (in accordance with the restrictions applicable to direct discharges to Puget Sound presented in Section 3.4.7 of Volume I of the SWMMWW) do not have to achieve the LID Version: June 2021 Packet Pg. 48 Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 16/25 Performance Standard, nor consider bioretention, rain gardens, permeable pavement, or full dispersion, but must meet the following: a. Projects must implement BMP T5.13 (Post -Construction Soil Quality & Depth); BMPs T5.10A Downspout Full Infiltration Systems, TS.lOB Downspout Dispersion Systems, or T5.1 OB Perforated Stub -out Connections; and BMP T5.11 Concentrated Flow Dispersion or T5.12 Sheet Flow Dispersion; if feasible for all new plus replaced hard surfaces and land disturbed. See the SWMMWW and the Edmonds Stormwater Addendum for additional details on On -site Stormwater Management BMP infeasibility V. Projects that do not drain directly or indirectly to the City's MS4 are required to implement one of the following: a. Project sites may discharge to the downstream private property (e.g., projects located above BNSF property) with approval from the downstream property owner(s). b. Project sites may discharge runoff to an on -site system. For sites located within earth subsidence and landslide hazard areas or their buffers, a geotechnical design, analysis, and report by a geotechnical engineer is required for the on -site system. On -site Stormwater Management BMPs from List No.1 in ECDC 18.30.060.D.5.d shall be evaluated for all new plus replaced hard surfaces and land disturbed. Projects are not required to evaluate BMPs in priority order or document infeasibility. The project applicant may be subject to an extra permit processing fee for City review of the geotechnical analysis. Projects are required to comply with all other applicable City requirements, such as ECDC 19.10 (earth subsidence and landslide hazard areas). ii. For sites located outside earth subsidence and landslide hazard areas or their buffers, ECDC 18.30.060.D.5.ii and ECDC 18.30.060.D.5.iii shall be followed to evaluate site appropriate BMP's. c. Subject to prior approval by the City, project sites may pump on -site runoff to the City's MS4. A quantitative downstream analysis in accordance with Minimum Requirement No. 4 and the Edmonds Stormwater Addendum will be required. If the City's MS4 does not have adequate capacity to receive the applicant's pumped flows, the applicant is required to install an on -site detention system to store runoff and pump it to the MS4 at an approved rate. vi. Projects under 2,000 SF of new plus replaced hard surfaces which discharge to an existing BMP with a surfaces overflow, shall expand the BMP size for the proposed new plus replaced hard surfaces based on existing design data. Alternatively, or where existing design data can not be found, the project shall discharge to a separate system appropriate sized per the designer. c. LID Performance Standard For projects that elect to meet the LID Performance Standard to comply with ECDC 18.30.060.D.b (ii) and (iii), Stormwater discharges shall match developed discharge durations to pre -developed durations for the range of pre -developed discharge rates from 8 percent of the 2-year peak flow to 50 percent of the 2-year peak flow from the project site. Refer to the Standard Flow Control Requirement section in Minimum Requirement No. 7 for information about the assignment of the pre -developed condition. Project sites that must also meet Minimum Requirement No. 7 shall match flow durations between 8 percent of the 2-year flow through the full 50-year flow. Version: June 2021 Packet Pg. 49 Edmonds Page 17/25 Chapter 18.30 STORM WATER MANAGEMENT i. Projects meeting the LID performance criteria are still required to comply with the requirements for BMP T5.13: Post -Construction Soils Quality and Depth, to the maximum extent feasible. d. List No.I for Category 1 project sites: On -site Stormwater Management BMPs for Projects Triggering Minimum Requirements No. 1 through No. 5. For projects that elect to use List No. 1 to comply with ECDC 18.30.060.D.b (ii), for each surface, consider the BMPs in the order listed for that type of surface. Use the first BMP that is considered feasible. No other On -site Stormwater Management BMP is necessary for that surface. Feasibility shall be determined by evaluation against design criteria, limitations, and infeasibility criteria identified for each BMP in the SWMMWW and the Edmonds Stormwater Addendum; and Competing Needs Criteria listed in Chapter 3 of Volume I of the SWMMWW. Lawn and landscaped areas: Roofs: Post -Construction Soil Quality and Depth in accordance with BMP T5.13 in Volume V of the SWMMWW. Full Dispersion in accordance with BMP T5.30 in Volume V of the SWMMWW. ii. Downspout Full Infiltration Systems in accordance with BMP T5.10A in Volume V of the SWMMWW. iii. Rain Gardens in accordance with BMP T5.14 or Bioretention in accordance with BMP T7.30 of Volume V of the SWMMWW. The rain garden or bioretention facility must have a minimum horizontal projected surface area below the overflow which is at least 5 percent of the area draining to it. iv. Downspout Dispersion Systems in accordance with BMP T5.1 OB in Volume V of the SWMMWW. V. Detention vaults or pipes in accordance with the Edmonds Stormwater Addendum 6.3. vi. Perforated Stub -out Connections in accordance with BMP T5.1 OC in Volume V of the SWMMWW. Other Hard Surfaces: Full Dispersion in accordance with BMP T5.30 in Volume V of the SWMMWW. ii. Full infiltration for equivalent surfaces areas per BMP T5.10A and/or Permeable Pavement in accordance with BMP T5.15 in Volume V of the SWMMWW, or iii. Rain Gardens in accordance with BMP T5.14 or Bioretention in accordance with BMP T7.30of Volume V of the SWMMWW. The rain garden or bioretention facility must have a minimum horizontal projected surface area below the overflow which is at least 5 percent of the area draining to it. iv. Sheet Flow Dispersion in accordance with BMP T5.12, or Concentrated Flow Dispersion in accordance with BMP T5.11 in Volume V of the SWMMWW. V. Detention vaults or pipes in accordance with the Edmonds Stormwater Addendum 6.3. e. List No.2 for Category 2 project sites: On -site Stormwater Management BMPs for Projects Triggering Minimum Requirements No. 1 through No. 9. Version: June 2021 Packet Pg. 50 Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 18/25 For projects that elect to use List No. 2 to comply with ECDC 18.30.060.D.b (iii), for each surface, consider the BMPs in the order listed for that type of surface. Use the first BMP that is considered feasible. No other On -site Stormwater Management BMP is necessary for that surface. Feasibility shall be determined by evaluation against design criteria, limitations, and infeasibility criteria identified for each BMP in the SWMMWW; and Competing Needs Criteria listed in Chapter 3 of Volume I of the SWMMWW. Lawn and landscaped areas: Roofs: Post -Construction Soil Quality and Depth in accordance with BMP T5.13 in Volume V of the SWMMWW. Full Dispersion in accordance with BMP T5.30 in Volume V of the SWMMWW. ii. Downspout Full Infiltration Systems in accordance with BMP T5.I OA in Volume V of the SWMMWW. iii. Bioretention in accordance with BMP T7.30 of Volume V of the SWMMWW. The rain garden or bioretention facility must have a minimum horizontal projected surface area below the overflow which is at least 5 percent of the area draining to it. iv. Downspout Dispersion Systems in accordance with BMP T5.1 OB in Volume III of the Downspout Dispersion Systems in accordance with BMP T5.1 OB in Volume III of the Downspout Dispersion Systems in accordance with BMP T5.1 OB in Volume III of the V. Detention vaults or pipes in accordance with the Edmonds Stormwater Addendum 6.3. vi. Perforated Stub -out Connections in accordance with BMP T5.1 OC in Volume III of the SWMMWW. Other Hard Surfaces: Other Hard Surfaces: Other Hard Surfaces: Other Hard Surfaces: i. F 11 Di persion in accordance with BMP T5.30 in Volume V of the Other Ha�",J Other Ha �Fgiion for equivalent surfaces areas per BMP T5.I OA in Volume III of the SWMMWW and/or Permeable pavement in accordance with BMP T5.15 in Volume V of the SWMMWW. iii. Bioretention (See Volume V of the SWMMWW) facilities that have a minimum horizontally projected surface area below the overflow which is at least 5 percent of the total surface area draining to it. iv. Sheet Flow Dispersion in accordance with BMP T5.12, or Concentrated Flow Dispersion in accordance with BMP T5.11 in Volume V of the SWMMWW. V. Detention vaults or pipes in accordance with the Edmonds Stormwater Addendum 6.3. Version: June 2021 Packet Pg. 51 Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 19/25 f. Overflows: All non -dispersion BMPs sized solely for Minimum Requirement #5 are anticipated to have an overflow discharge on a semi -regular basis and therefore requires a sub -surface piped connection directly to the MS4 system. i. In order to eliminate a piped overflow connection, the project shall be designed to infiltrate 100% of the modelled 100-year storm per continuous modeling. A safe and certain surface overflow path must still be provided and may not negatively impact adjacent properties. ii. In cases where the City MS4 is not in a location where a reasonable connection can be made for a project in capable of fully infiltrating per ECDC 18.30.060.D.5.fi above: • Extensions equal to or less than the length of the project frontage would be anticipated and generally not consider for an exception to 18.30.060.D.5.f.i. • Extension exceeding the project frontage length will be considered on a case -by -case basis for exception to 18.30.060.D.5.f.i. Minimum Requirement No. 6 — Runoff Treatment a. Project Thresholds: When assessing road -related projects against the following thresholds, only consider those hard and pervious surfaces that are subject to this minimum requirement per ECDC 18.30.060.C.2. For all other projects, the requirements apply to the new plus replaced hard surfaces and the converted vegetation areas. The following require construction of stormwater treatment facilities: Projects in which the total of pollution -generating hard surface (PGHS) is 5,000 square feet or more in a threshold discharge area of the project, or ii. Projects in which the total of pollution -generating pervious surfaces (PGPS) — not including permeable pavements — is 0.75 acres or more in a threshold discharge area, and from which there will be a surface discharge in a natural or man-made conveyance system from the site. b. Treatment -Type Thresholds and Facility Sizing: Treatment -Type Thresholds in accordance with Section 1.2, Volume III of the SWMMWW Phosphorus treatment shall be required for projects draining to Hall Creek and Lake Ballinger. ii. Treatment Facility Sizing, including Water Quality Design Storm Volume, Water Quality Design Flow Rate, and Downstream Facilities, in accordance with Chapter 3, Section 3.4.6, Volume I of the SWMMWW. c. Treatment Facility Selection, Design, and Maintenance Stormwater treatment facilities shall be: Selected in accordance with the process identified in Chapter 1 of Volume III of the SWMMWW, ii. Designed in accordance with the design criteria in Volume V of the SWMMWW, and iii. Maintained in accordance with the maintenance schedule in Volume V of the SWMMWW. d. Additional Requirements The discharge of untreated stormwater from pollution -generating hard surfaces to ground water will not be authorized by the City except for infiltration or dispersion of runoff through BMPs designed and implemented per ECDC 18.30 and SWMMWW. Minimum Requirement No. 7 — Flow Control Version: June 2021 Packet Pg. 52 Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 20/25 a. Applicability: Flow control is required on projects meeting the thresholds summarized below to reduce the impacts of stormwater runoff from hard surfaces and land cover conversions. Flow control in accordance with Minimum Requirement No. 7 is not required for projects that discharge directly to, or indirectly through the City's MS4 to Puget Sound subject to the restrictions of the TDA Exemption (aka. direct discharge exemption) per SWMMWW Section 3.4.7 of Volume I (other minimum requirements may still apply). See ECDC 18.30.060.D.5.b.iv and Section 3.4.7 of Volume I of the SWMMWW for additional restrictions applicable to direct discharges to Puget Sound. If the discharge drains to a stream that leads to a wetland, or to a wetland that has an outflow to a stream, both this minimum requirement (Minimum Requirement No. 7) and Minimum Requirement No. 8 apply. b. Thresholds: When assessing road -related projects against the following thresholds, only consider only those impervious, hard, and pervious surfaces that are subject to this minimum requirement per ECDC 18.30.060.C.2. For all other projects, the requirements apply to the new plus replaced hard surfaces and the converted vegetation areas. The following circumstances require achievement of the standard flow control requirement for western Washington: Projects in which the total of effective impervious surfaces is 10,000 square feet or more in a threshold discharge area, or ii. Projects that convert 0.75 acres or more of vegetation to lawn or landscape, or convert 2.5 acres or more of native vegetation to pasture in a threshold discharge area, and from which there is a surface discharge in a natural or man-made conveyance system from the site, or iii. Projects that through a combination of hard surfaces and converted vegetation areas cause a 0.10 cubic feet per second (cfs) increase or greater in the 100-year flow frequency from a threshold discharge area as estimated using the Western Washington Hydrology Model or other approved model and one -hour time steps (or a 0.15 cfs increase or greater using 15- minute time steps). Standard Flow Control Requirement (applies to discharges directly or indirectly to the City's MS4, except for projects that meet the direct discharge requirements outlined in "a" above and/or projects discharging to Perrinville Creek): Stormwater discharges shall match developed discharge durations to pre -developed durations for the range of pre -developed discharge rates from 50 percent of the 2-year peak flow up to the full 50-year peak flow. The pre -developed condition to be matched shall be a forested land cover unless reasonable, historic information is available that indicates the site was prairie prior to settlement (modeled as "pasture" in the Western Washington Hydrology Model). This standard requirement is waived for sites that will reliably infiltrate all the runoff from hard surfaces and converted vegetation areas. d. Perrinville Basin Flow Control Standard (applies to all discharges within the Perrinville Creek basin) shall be an elevated level of flow control design. Discharges to the Perrinville Creek Basin shall maintain the durations of high flows at their predevelopment levels for all flows greater than one-half of the 2-year flow up to the 50-year flow AND holding the 100-year peak flow rate at its predevelopment level. The predevelopment peak flow rates for the 2-year and 10-year runoff events are also intended to be maintained. e. Additional Requirement: Flow Control BMPs shall be selected, designed, and maintained in accordance with Volume III of the SWMMWW or an approved equivalent. 8. Minimum Requirement No. 8 — Wetlands Protection a. Applicability: The requirements below apply only to projects whose stormwater discharges into a wetland, either directly or indirectly through a conveyance system. Version: June 2021 Packet Pg. 53 Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 21/25 b. Thresholds: The thresholds identified in Minimum Requirement No. 6 — Runoff Treatment, and Minimum Requirement No. 7 — Flow Control shall also be applied to determine the applicability of this requirement to discharges to wetlands. c. Standard Requirement: Projects shall comply with Guide Sheets No. 1 through No. 3 in Appendix I-D of the SWMMWW. The hydrologic analysis shall use the existing land cover condition to determine the existing hydrologic conditions unless directed otherwise by a regulatory agency with jurisdiction. d. Additional Requirements: Stormwater treatment and flow control facilities shall not be built within a natural vegetated buffer, except for: Necessary conveyance systems as approved by the City; or ii. As allowed in wetlands approved for hydrologic modification or treatment in accordance with Guide Sheet 2 in Appendix I-D of the SWMMWW. An adopted and implemented basin plan prepared in accordance with the provisions of Section 7 of Appendix 1 of the Phase II NPDES Municipal Stormwater Permit. 9. Minimum Requirement No. 9 — Operation and Maintenance An operation and maintenance manual that is consistent with the provisions in Volume I and Volume V of the SWMMWW is required for proposed Stormwater Treatment and Flow Control BMPs/facilities. The party (or parties) responsible for maintenance and operation shall be identified in the operation and maintenance manual. For private facilities approved by the City, a copy of the operation and maintenance manual shall be retained on -site or within reasonable access to the site, and shall be transferred with the property to the new owner. For public facilities, a copy of the operation and maintenance manual shall be retained in the appropriate department. A log of maintenance activity that indicates what actions were taken shall be kept and be available for inspection. 18.30.070 Exceptions, Adjustments, and Appeals. A. Exceptions. 1. The Director may approve a request for an exception to the minimum requirements of this chapter following legal public notice of an application for an exception and of the Director's decision on the application. All legal public notice related to this request for an exception shall be in the manner prescribed in ECDC 20.03.002 and the applicant shall pay all costs to publish the legal public notices required by this provision. The Director shall provide and keep written findings of fact of the decision. 2. The approval of the exception shall only be granted when the applicant demonstrates that the requirement would cause a severe and unexpected economic hardship. To determine whether the requirement imposes a severe and unexpected economic hardship on the project applicant, the applicant must document for City review and approval, all of the following, at a minimum: a. The current, pre -project use of the site; and b. How application of the requirement(s) for which an exception is being requested restricts the proposed use of the site compared to the restrictions that existed prior to adoption of this chapter; and c. The possible remaining uses of the site if the exception were not granted; and d. The possible uses of the site that would have been allowed prior to the adoption of this chapter; and e. A comparison of the estimated amount and percentage of value loss as a result of the requirements versus the estimated amount and percentage of value loss as a result of requirements that existed prior to adoption of the requirements of this chapter; and Version: June 2021 Packet Pg. 54 Edmonds Chapter 18.30 STORM WATER MANAGEMENT f. The feasibility of the applicant to alter the project to apply the requirements of this chapter. 3. Any exception must meet the following criteria: Page 22/25 a. The exception will not increase risk to the public health and welfare, nor be injurious to other properties in the vicinity and/or downstream, and to the quality of waters of the state; and b. The exception is the least possible exception that could be granted to comply with the intent of the minimum requirements. 4. An exception to the requirements shall only be granted to the extent necessary to provide relief from the economic hardship as determined by the Director, to alleviate the harm or threat of harm to the degree that compliance with the requirement becomes technically feasible, or to perform the emergency work that the Director determines is warranted. 5. The Director may require an applicant to provide additional information at the applicant's expense, including (but not limited to) an engineer's report or analysis. 6. When an exception is granted, the Director may impose new or additional requirements to offset or mitigate harm or the threat of harm that may be caused by granting the exception, or that would have been prevented if the exception had not been granted. B. Adjustments. 1. The Director may approve a request for adjustments to the requirements of this chapter when the Director finds that: a. The adjustment provides substantially equivalent environmental protection; and b. The objectives of safety, function, environmental protection, and facility maintenance are met, based on sound engineering practices. During construction, the Director may require, or the applicant may request, that the construction of drainage control facilities and associated project designs be adjusted if physical conditions are discovered on the site that are inconsistent with the assumptions on which the approval was based, including (but not limited to) unexpected soil or water conditions, weather -generated problems, or changes in the design of the improved areas; and A request by the applicant for an adjustment shall be submitted to the Director for review and approval prior to implementation. The request shall be in writing and shall provide facts substantiating the requirements of subsection (C)(1) of this section, and if made during construction, the factors in subsection (C)(2) of this section. Any such modifications made during the construction of drainage control facilities shall be included with the final approved drainage control plan. C. Appeal. 1. The Director's decision on an application for an exception or adjustment may appeal to the hearing examiner in accordance with a Type II appeal process in ECDC Chapter 20.06. 2. The applicant shall carry the burden of proof. 3. The decision of the hearing examiner is appealable to superior court in accordance with Chapter 36.70C RCW. [Ord. 3792 § 1, 2010]. 18.30.080 Access and Covenants. A. Access. Proper ingress and egress shall be provided to the City to inspect or perform any duty imposed upon the City by this Title. The City shall notify the responsible party in writing of a failure to provide access. If the Version: June 2021 Packet Pg. 55 Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 23/25 responsible party fails to respond within seven days from the receipt of notification, the City may order the work required to be completed or otherwise address the cause of improper access. The obligation for the payment of all cost that may be incurred or expended by the City in causing such work to be done shall be imposed on the person holding title to the subject property. B. Covenants. Maintenance covenants shall be required for each site/lot that will be maintained by a private entity such as an individual, corporation, or homeowner's association. The maintenance covenant shall address or append requirements and responsibilities for long-term management and maintenance the applicable BMP(s). Maintenance covenants shall be as specified in City Engineering Division documents or approved by the Director, and recorded with Snohomish County and on all proper deeds [Ord. 3792 § 1, 2010]. 18.30.090 Post Construction Inspection and Maintenance Roles and Responsibilities. Proper construction inspection and maintenance of stormwater facilities is essential for the protection of the City's MS4 and the environment. A. Stormwater Maintenance and Inspection Standards. Stormwater facilities shall be inspected and maintained per the requirements of Volume I and Volume V of the SWMMWW. For systems which do not have a maintenance standard, the owner shall develop a standard based on guidelines from the manufacturer, designer, or a registered professional engineer and submit the standards to the Director for approval. The purpose of the maintenance standard is to determine if maintenance is required. The maintenance standard is not a measure of the facility's required condition at all times between inspections. Exceeding the maintenance standard between inspections is not a violation of this chapter. B. Ownership. Stormwater facilities are either privately or publicly owned and maintained. All stormwater facilities that serve private property are private, unless an agreement between the property owner and the City states otherwise. Stormwater facilities that are privately owned by a homeowner's association or similar organization also are private. The City may offer an incentive program to owners to support the proper maintenance of private storm drainage facilities. C. Public Stormwater Facilities. The City shall be responsible for operating, maintaining, repairing, and replacing public stormwater facilities as funded through the Stormwater Utility. D. Maintenance and Inspection of Permanent Facilities. All privately owned storm drainage facilities or controls shall be maintained by the owner, or the homeowner or owner association ("owner") if one is established as part of a residential or commercial development. All private storm drainage facilities shall be regularly inspected to ensure proper operation and shall monitor the facility or control as required or as set forth in the SWMMWW. The Owner shall maintain records of inspection and maintenance, disposal receipts, and monitoring results. The records shall catalog the action taken, the person who took it, the date said action was taken, how it was done, and any problems encountered or follow-up actions required. The records shall be made available to the City upon request. The Owner shall maintain a copy of the Stormwater Operations and Maintenance Manual (if required) on site, and shall make reference to such document in real property records filed with Snohomish County, so others who acquire real property served by the privately owned storm drainage facilities or controls are notified of their obligation to maintain such facilities or controls. E. City Inspection of private stormwater facilities. The City shall have the authority to periodically inspect private stormwater facilities, including low impact development stormwater facilities, for compliance with this chapter. F. Right of Entry. An authorized representative of the City may enter private property at all reasonable times to conduct inspections, tests or to carry out other duties imposed by the a state or Federal program provided that the City makes a good faith effort to notify the property owner or person responsible for the premises prior to entering and presents proper credentials to that person. If entry is refused or cannot be obtained, the Director shall have recourse to every remedy provided by law to secure entry, including but not limited to, obtaining an administrative warrant for entry. Version: June 2021 Packet Pg. 56 2.4.a Edmonds Page 24/25 Chapter 18.30 STORM WATER MANAGEMENT G. Right of Entry for Illicit Discharge. In the event of an illicit discharge from a privately -owned stormwater facility caused by improper maintenance or operation or other circumstance, the provisions of ECC 7.200 shall apply. H. Maintenance Responsibilities. Upon written notice by the City, a private stormwater facility shall be promptly repaired and/or brought up to applicable standards by the property owner or the person responsible for said facility. If a private stormwater facility serves multiple lots and the responsibility for maintenance has not been specified on a recorded subdivision plat, short plat, or other legal document, maintenance, operation and repair responsibility shall rest with the homeowners' association, if one exists, or otherwise with the properties served by the facility, or finally, with the owners of the property on which the facilities are located. I. Disposal of Waste from Maintenance Activities. Disposal of waste from maintenance activities shall be conducted in accordance with the minimum Functional Standards for Solid Waste Handling, Chapter 173-304 WAC, guidelines for disposal of waste materials from storm water maintenance activities, and where appropriate, the Dangerous Waste Regulations, Chapter 173-303 WAC. 18.30.100 Enforcement Procedures. A. General enforcement action shall be in accordance with this chapter whenever a person has violated any provision of this chapter. The choice of enforcement action is at the discretion of the City. B. Civil Penalties Adopted. ECDC Chapter 20.110 enforcement procedures are herein adopted in full, as modified in this chapter, with the proviso that repeat offenders or violations deemed an immediate public hazard shall be subject to compliance and appeal timelines as deemed appropriate by the Director based on the specific nature of the violation. C. Maintenance Orders. The Director shall have the authority to issue to an owner or person an order to maintain or repair a component of a stormwater facility or BMP to bring it into compliance with this chapter, the SWMMWW, the Edmonds Stormwater Addendum, and the Edmonds Community Development Code. The order shall include: 1. A description of the specific nature, extent and time of the violation and the damage or potential damage that reasonably might occur; 2. A notice that the violation or the potential violation cease and desist and, in appropriate cases, the specific corrective actions to be taken; and 3. A reasonable time to comply, depending on the circumstances. D. Civil Penalty. A person who fails to comply with the requirements of this chapter, who fails to conform to an approval or order issued, who undertakes development without first obtaining approval, or who fails to comply with a stop work order issued under these regulations shall be subject to a civil penalty levied in accordance with the provisions of ECDC Chapter 20.110; provided, however, that the appeal process shall commence with a notice of violation as provided in ECDC 20.110.040.13. 1. Civil penalties for code violations shall be imposed in accordance with the provisions of ECDC Chapter 20.110; provided, however, that in addition to the penalties set forth in that chapter, the hearing examiner is authorized to levy a penalty of up to twenty thousand dollars ($20,000) per occurrence based upon an assessment of the following factors. Where such factors are present, the hearing examiner is authorized to levy such penalty after taking into consideration the full impact of the violation and any mitigating circumstances (see subsection (2) below): a. The violation created a risk to public health and the significance of the risk. b. The violation damaged the environment and the significance of the damage. c. The violation caused damage to public and private property and the significance of such damage. d. A history of similar violations, if any. Version: June 2021 Packet Pg. 57 2.4.a Edmonds Page 25/25 Chapter 18.30 STORM WATER MANAGEMENT e. The economic benefit of the violations, if any, to the person or entity responsible for the violations. 2. Mitigating circumstances which may be used to offset or reduce the time resulting from the application of the preceding factors are limited to: a. Full compliance with a voluntary compliance agreement and no history of similar violations. b. Full compliance with a voluntary compliance agreement and a history of one or two similar violations (lesser reduction). c. A "voluntary compliance agreement" is defined as a legally binding agreement entered into between the City and the alleged violators, by which the violator(s) acknowledge the existence of the violation, waive all appeal rights, and agree to and do pay a fine in an amount stipulated to between the violator and the City. If the violation(s) are not corrected as ordered, or a voluntary compliance agreement is not entered into within that time period and no appeal is filed, the penalty for the next 15-day period shall be 150 percent of the initial penalties, and the penalties for the next 15-day period shall be 200 percent of the initial penalties. The intent of this subsection is to increase penalties beyond the maximum penalties stated as an additional means to achieve timely compliance. Unless otherwise provided in a voluntary compliance agreement, civil penalties shall be paid within 30 days of service of the notice and order or stop work order if not appealed. Payment of the civil penalties assessed under this chapter does not relieve a person found to be responsible for a code violation of his or her duty to correct the violation or to pay any and all civil penalties or other cost assessments issued pursuant to this chapter. The City may suspend immediate payment of civil penalties if the person responsible for a code violation has entered into a voluntary compliance agreement. Penalties shall begin to accrue again pursuant to the terms of the voluntary compliance agreement if any necessary permits applied for are denied, canceled or not pursued, if corrective action identified in the voluntary compliance agreement is not completed as specified, or if the property is allowed to return to a condition similar to that condition which gave rise to the voluntary compliance agreement; provided, however, that additional penalties shall not be imposed until additional notice and opportunity for hearing have been provided in accordance with ECDC Chapter 20.110. Civil penalties assessed create joint and several personal obligations in all persons responsible for a code violation. E. The determination of the hearing examiner issued in accordance with ECDC Chapter 20.110 shall be appealable to the Snohomish County superior court in accordance with the provisions of Chapter 36.70C RCW. F. The remedies provided for in this section shall not be exclusive. The City may also use other civil and administrative remedies available to it, including but not limited to the remedies provided in ECDC Title 19 and the state building and dangerous buildings codes. Version: June 2021 Packet Pg. 58 2.4.b Edmonds Chapter 18.30 STORM WATER MANAGEMENT Chapter 18.30 STORMWATER MANAGEMENT Sections: 18.30.000 Purposes. 18.30.010 Definitions. 18.30.020 Authority and Regulation. 18.30.030 Applicability. 18.30.040 Exemptions. 18.30.050 Administration. 18.30.060 Requirements. 18.30.070 Exceptions, Adjustments, and Appeal. 18.30.080 Access and Covenants. 18.30.090 Post Construction Inspection and Maintenance Roles and Responsibilities. 18.30.100 Enforcement Procedures. 18.30.000 Purposes. Page 1/27 A. To set forth standards for managing stormwater runoff from construction and development sites to minimize 1. Degradation of surface water quality by controlling the scouring and sedimentation of creeks, streams, wetlands, ponds, lakes, other water bodies. 2. Degradation of groundwater quality. 3. Damage to adjacent and other downstream private properties from erosion or other impacts from stormwater runoff. 4. Damage of City -owned parcels, City roads, rights -of -way and associated infrastructure. B. To comply with requirements in the Phase II National Pollutant Discharge Elimination System (NPDES) Municipal Stormwater Permit as issued by the Washington State Department of Ecology (Ecology). C. To complement site planning activities that minimize: 1. Impervious surfaces area. 2. The loss of native or non-native site vegetation. 3. The generation of stormwater runoff. D. To make low impact development (LID) the preferred and commonly used approach to site development; to require LID be considered at the site planning stage; and to implement LID BMPs unless they are infeasible. E. To require that all publicly -owned and privately -owned Stormwater Treatment and Flow Control best management practices (BMPs)/Facilities are operated, maintained and repaired in manner that conforms to this chapter. F. To provide the authority for the City to inspect privately -owned Stormwater Treatment and Flow Control BMPs/Facilities. G. To provide enforcement procedures for ensuring compliance with this chapter. Version: September 4 20 5June 2021 Packet Pg. 59 Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 2/27 18.30.010 Definitions. For the purposes of this chapter, the following definitions shall apply: Arterial. A road or street primarily for through traffic. The term generally includes roads or streets considered collectors. It does not include local access roads which are generally limited to providing access to abutting property. See also RCW 35.78.010, RCW 36.86.070, and RCW 47.05.021. Adjustment. A variation in the application of a minimum requirement to a particular project. Adjustments provide substantially equivalent environmental protection. Applicant. The owning individual(s) or corporations or their representatives applying for the permits or approvals described in this chapter. Approval. The proposed work or completed work conforming to this chapter as approved by the public works Director or their designee. Best management practices (BMPs). The schedules of activities, prohibitions of practices, maintenance procedures, and structural and/or managerial practices approved by the City that, when used singly or in combination, prevent or reduce the release of pollutants and other adverse impacts to waters of Washington State. Bioretention BMPs. Engineered facilities that treat stormwater by passing it through a specified soil profile, and either retain or detain the treated stormwater for flow attenuation. Refer to the 2-04.4-2019 Stonrynwater Management Manual for Western Washington (SWMMWW), r'iaiVolume V for bioretention BMP types and design specifications. Category 1 Project Site. A project site subject to Minimum Requirements No.I through No.5. See ECDC 18.30.60. C. Category 2 Project Site. A project site subject to Minimum Requirements No.I through No.9. See ECDC 18.30.60.C. Certified Erosion and Sediment Control Lead (CESCL). An individual who has current certification through an approved erosion and sediment control training program that meets the minimum training standards established by Ecology (see BMP C160 in the SWMMWW). A CESCL is knowledgeable in the principles and practices of erosion and sediment control. The CESCL must have the skills to assess site conditions and construction activities that could impact the quality of stormwater and, the effectiveness of erosion and sediment control measures used to control the quality of stormwater discharges. Certification is obtained through an Ecology approved erosion and sediment control course. Course listings are provided online at Ecology's website. City's municipal separate storm sewer system or "MS4." A conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, manmade channels, or storm drains) that are owned or operated by the City of Edmonds, designed or used for collecting or conveying stormwater, and are not a combined sewer nor part of a publicly owned treatment works as defined in 40 Code of Federal Regulations (CFR) 122.2, and which is defined as "large" or "medium" or "small" or otherwise designated by Ecology pursuant to 40 CFR 122.26. Clearing. The destruction and removal of vegetation by manual, mechanical, or chemical methods. Commercial Agriculture. Those activities conducted on lands defined in RCW 84.34.020(2) and activities involved in the production of crops or livestock for commercial trade. An activity ceases to be considered commercial agriculture when the area on which it is conducted is proposed for conversion to a nonagricultural use or has lain idle for more than five years, unless the idle land is registered in a federal or state soils conservation program, or unless the activity is maintenance of irrigation ditches, laterals, canals, or drainage ditches related to an existing and ongoing agricultural activity. Common plan of development or sale. A site where multiple separate and distinct construction activities may be taking place at different times on different schedules and/or by different contractors, but still under a single plan. Version: September 4 20 5June 2021 Packet Pg. 60 2.4.b Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 3/27 Examples include: 1) phase projects and projects with multiple filings or lots, even if the separate phases or filings/lots will be constructed under separate contract or by separate owners (e.g., a development where lots are sold to separate builders); 2) a development plan that may be phased over multiple years, but is still under a consistent plan for long-term development; 3) projects in a contiguous area that maybe unrelated but still under the same contract, such as construction of a building extension and a new parking lot at the same facility; and 4) linear projects such as roads, pipelines, or utilities. If the project is part of a common plan of development or sale, the disturbed area of the entire plan must be used in determine permit requirements. Converted vegetation (areas). The change in land cover changed from native vegetation, pasture scrub/shrub, or unmaintained non-native vegetation to lawn or landscaped areas, or where native vegetation is converted to pasture. Creek. Is synonymous with "streams," which is defined in ECDC 23.40.320. Detention facility. An above or below ground facility, such as a pond or tank, that temporarily stores stormwater runoff and subsequently releases it at a slower rate than it is collected by the drainage facility system. There is little or no infiltration of stored stormwater. Development. Land -disturbing activities, including Class IV general forest practices that are conversions from timber land to other uses. Creation or addition of hard surfaces, or replacement of hard surface that is not part of a routine maintenance activity. Structural development, including construction, installation, replacement, or expansion of a building or other structure. Subdivision, short subdivision, and binding site plans, as defined and applied in Chapter 58.17 RCW Director. The City's Public Works and Utilities Director or a designee with an appropriate background in engineering or another related discipline. Discharge point. The location where a discharge leaves the municipal separate storm sewer system (MS4) through the City's MS4 facilitiesBMPs designed to infiltrate. Ecology. The Washington State Department of Ecology. Effective impervious surface. Those impervious surfaces that are connected via sheet flow or discrete conveyance to a drainage system. Impervious surfaces on residential development sites are considered ineffective if: 1) the runoff is dispersed through at least 100 feet of native vegetation in accordance with BMP T5.30 — "Full Dispersion," as described in Chapter 5 of Volume V of the SWMMWW; 2) residential roof runoff is infiltrated in accordance with downspout Full Infiltration Systems in BMP T5.10A in Volume III of the SWMMWW; or 3) approved continuous runoff modeling methods indicate the entire runoff file is infiltrated. Erodible or leachable materials. Wastes, chemicals, or other substances that measurably alter the physical or chemical characteristics of runoff when exposed to rainfall. Examples include erodible soils that are stockpiled, uncovered process wastes, manure, fertilizers, oily substances, ashes, kiln dust, and garbage dumpster leakage. Erosion. The wearing away of the land surface by running water, wind, ice, or other geological agents, including such processes as gravitational creep. Also, detachment and movement of soil or rock fragments by water, wind, ice, or gravity. See the SWMMWW Glossary for examples of types of water erosion. Excavation. The mechanical removal of earth material. Exception. Relief from the application of a minimum requirement to a project. Fill. A deposit of earth material placed by artificial means. Groundwater. Water in a saturated zone or stratum beneath the land surface or below a water body. Hard surface. An impervious surface, a permeable pavement, or a vegetated roof. Version: September 4 20 5June 2021 Packet Pg. 61 2.4.b Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 4/27 Highway. A main public road connecting towns and cities. In Edmonds, this includes State Route 99, State Route 524, and portions of State Route 104, that are classified as principal arterials in the City's comprehensive transportation plan. Illicit discharge. Any direct or indirect non-stormwater discharge to the City's MS4, groundwaters, or a water body, except as expressly allowed by ECDC Chapter 7.200. Impervious surface. A non -vegetated surface area that either prevents or retards the entry of water into the soil mantle as under natural conditions prior to development. A non -vegetated surface area which causes water to run off the surface in greater quantities or at an increased rate of flow from the flow present under natural conditions prior to development. Common impervious surfaces include, but are not limited to, roof tops, walkways, patios, driveways, parking lots or storage areas, concrete or asphalt paving, gravel roads, packed earthen materials, and oiled, macadam or other surfaces that similarly impede the natural infiltration of stormwater. Open, uncovered retention/detention facilities shall not be considered impervious surfaces for purposes of determining whether the thresholds for application of minimum requirements are exceeded. Open, uncovered retention/detention facilities shall be considered impervious surfaces for purposes of runoff modeling. Outdoor swimming pools shall be considered impervious surfaces in all situations. In addition, lawns, landscaping, sports fields, golf courses, and other areas that have modified runoff characteristics resulting from the addition of underdrains and impermeable or low permeability liners are to be considered impervious surfaces. If no liner is installed, these areas (lawns, landscaping, sports fields, golf courses, etc.) served by underdrains may be considered partially pervious if the underdrain is set a minimum of 8 inches above the in -situ soils in a manner to allow infiltration over the facility bottom. Lake. An inland body of fresh water surrounded by land. Land disturbing activity. Any activity that results in a change in the existing soil cover (both vegetative and non - vegetative) and/or the existing soil topography. Land -disturbing activities include but are not limited to demolition, clearing, grading, filling, and excavation. Compaction that is associated with stabilization of structures and road construction shall also be considered a land -disturbing activity. Vegetation maintenance practices, including landscape maintenance and gardening, are not considered land -disturbing activity. Stormwater facility maintenance is not considered land disturbing activity if conducted according to established standards and procedures. Low impact development (LID). A stormwater and land use strategy that strives to mimic pre -disturbance hydrologic processes of infiltration, filtration, storage, evaporation and transpiration by emphasizing conservation, use of on -site features, site planning, and distributed stormwater management practices that are integrated into a project design. LID Best Management Practices (BMPs). Distributed stormwater management practices, integrated into a project design, that emphasize pre -disturbance hydrologic processes of infiltration, filtration, storage, evaporation and transpiration. LID BMPs include, but are not limited to, bioretention, rain gardens, permeable pavements, roof downspout controls, dispersion, soil quality and depth, minimal excavation foundations, vegetated roofs, and water re -use. LID principles. Land use management strategies that emphasize conservation, use of on -site natural features, and site planning to minimize impervious surfaces, native vegetation loss, and stormwater runoff. Maintenance. Repair and maintenance activities conducted on currently serviceable structures, facilities, and equipment that involves no expansion or use beyond that previously existing and results in no significant adverse hydrologic impact. It includes those usual activities taken to prevent a decline, lapse, or cessation in the use of structures and systems. Those usual activities may include replacement of dysfunctional facilities, including cases where environmental permits require replacing an existing structure with a different type structure, as long as the functioning characteristics of the original structure are not changed. One example is the replacement of a collapsed, fish blocking, round culvert with a new box culvert under the same span, or width, of roadway. In regard to stormwater facilities, maintenance includes assessment to ensure ongoing proper operation, removal of built up pollutants (i.e., sediments), replacement of failed or failing treatment media, and other actions taken to correct defects as identified in the maintenance standards of Chapter-4Appendix A, Volume V of the SWMMWW. Version: September 4 20 5June 2021 Packet Pg. 62 2.4.b Edmonds Page 5/27 Chapter 18.30 STORM WATER MANAGEMENT Maximum extent practicable (MEP). Refers to paragraph 402(p)(3)(B)(iii) of the federal Clean Water Act which reads as follows: Permits for discharges from municipal storm sewers shall require controls to reduce the discharge of pollutants to the maximum extent practicable, including management practices, control techniques, and system, design, and engineering methods, and other such provisions as the Administrator or the State determines appropriate for the control of such pollutants. MS4. The City's municipal separate storm sewer system. Native vegetation. Vegetation comprised of plant species, other than noxious weeds, indigenous to the coastal region of the Pacific Northwest which could have been reasonably expected to occur naturally on the site. Examples include trees such as Douglas fir, western hemlock, western red cedar, alder, big -leaf maple, and vine maple; shrubs such as willow, elderberry, salmonberry, and salal; and herbaceous plants such as sword fern, foam flower, and fireweed. Natural drainage systems and outfalls. The location of the channels, swales, and other non -manmade conveyance systems as defined by the earliest documented topographic contours existing for the subject property, either from maps or photographs, or such other means as appropriate. New Development. Land disturbing activities, including Class IV -general forest practices that are conversions from timberland to other uses; structural development, including construction or installation of a building or other structure; creation of hard surfaces; and subdivision, short subdivision, and binding site plans, as defined and applied in Chapter 58.17 RCW. ECDC 18.30 does not distinguish the difference between new development and redevelopment: all proiects in Edmonds shall meet the reauirements for new development. New Impervious Surface. A surface that is: 1) changed from a pervious surface to an impervious surface (e.g_ resurfacing by upgrading from dirt to gravel, a bituminous surface treatment ("chip seal"), asphalt, concrete, or an impervious structure); or 2) upgraded from gravel to chip seal, asphalt, concrete, or an impervious structure; or 3) upgraded from chip seal to asphalt, concrete, or an impervious structure. Note that if asphalt or concrete has been overlaid by seal, the existing condition should be considered as asphalt or concrete. Outfall. A point source as defined by 40 CFR 122.2 at the point where a discharge leaves the City's MS4 and enters a surface receiving waterbody or surface receiving waters. Outfall does not include pipes, tunnels, or other conveyances which connect segments of the same stream or other surface waters and are used to convey primarily surface waters (i.e., culverts). On -site Stormwater Management BMPs. A synonym for Low Impact Development BMPs. Permeable pavement. Pervious concrete, porous asphalt, permeable pavers or other forms of pervious or porous paving material intended to allow passage of water through the pavement section. It often includes an aggregate base that provides structural support and acts as a stormwater reservoir. Pervious Surface. Any surface material that allows stormwater to infiltrate into the ground. Examples include lawn, landscape, pasture, native vegetation areas, and permeable pavements. Person. Any individual, partnership, corporation, association, organization, cooperative, public or municipal corporation, agency of the state, or City government unit, however designated. Pollution -generating hard surface (PGHS). Those hard surfaces considered to be a significant source of pollutants in stormwater runoff. See the listing of surfaces under pollution -generating impervious surface. Pollution -generating impervious surface (PGIS). Those impervious surfaces considered to be a significant source of pollutants in stormwater runoff. Such surfaces include those which are subject to: vehicular use; industrial activities (as further defined in the glossary of the SWMMWW); storage of erodible or leachable materials, wastes, or chemicals, and which receive direct rainfall or the run-on or blow-in of rainfall; metal roofs unless they are coated with an inert, non -leachable material (e.g., baked -on enamel coating); or roofs that are subject to venting significant amounts of dusts, mists, or fumes from manufacturing, commercial, or other indoor activities. Version: September 4 20 5June 2021 Packet Pg. 63 2.4.b Edmonds Page 6/27 Chapter 18.30 STORM WATER MANAGEMENT Pollution -generating pervious surfaces (PGPS). Any pervious surface subject to )—vehicular use, 2)L industrial activities (as further defined in the glossary of the SWMMWW); or 31storage of erodible or leachable materials, wastes, or chemicals, and that receive direct rainfall or run-on or blow-in of rainfall, use of pesticides and fertilizers, or Sloss of soil. Typical PGPS include permeable pavement subject to vehicular use, lawns, and landscaped areas including: golf courses, parks, cemeteries, and sports fields (natural and artificial turf). Pre -developed condition. The native vegetation and soils that existed at a site prior to the influence of Euro- American settlement. The pre -developed condition shall be assumed to be a forested land cover unless reasonable, historic information is provided that indicates the site was prairie prior to settlement. Project: Any proposed action to alter or develop a site. Project site. That portion of a property, properties, and/or right-of-way subject to land -disturbing activities, new hard surfaces, or replaced hard surfaces. For projects that involve land disturbing activity on one or more parcels and/or land disturbing activity in the City right-of-way, the "Project site" includes all areas of land disturbance. If the project is part of a common development plan or sale, the disturbed area of the entire plan shall be used in determining permit requirements. Rain garden. A non -engineered shallow landscaped depression, with compost -amended native soils and adapted plants. The depression is designed to pond and temporarily store stormwater runoff from adjacent areas, and to allow stormwater to pass through the amended soil profile. Receiving waterbody or Receiving waters. Naturally and/or reconstructed naturally occurring surface water bodies, such as creeks, streams, rivers, lakes, wetlands, estuaries, and marine waters, or groundwater, to which a MS4 discharges. Redevelopment. ECDC 18.30 does not distinguish the difference between new development and redevelopment; all projects in Edmonds shall meet the requirements for new development. Where existing unmitigated surfaces are to remain, the additional "retro-fit" requirement per ECDC 18.30.060.D.5.b.i Replaced hard surface. For structures means the removal and replacement of hard surfaces down to the foundation. For other hard surfaces, it means the removal down to bare soil or base course and replacement. Replaced impervious surface. For structures, the removal and replacement of any exterior impervious surfaces down to the foundation. For other impervious surfaces, it means the removal down to bare soil or base course and replacement. Roadway. Traveled hard surface portion of any public or private road or street. Road -related project. A project that all of, or the majority of, the new or replaced hard surface consist of roadway, shoulders, curbs, gutters, sidewalks, or walkways, either publicly or privately funded. Frontage improvements constructed as a requirement for a development project are not consider a road -roadway project. Runoff. Water originating from rainfall and other precipitation that is found in drainage facilities, rivers, streams, springs, seeps, ponds, lakes and wetlands, as well as shallow ground water. It also means the portion of rainfall or other precipitation that becomes surface flow and interflow. Site. The area defined by the legal boundaries of a parcel or parcels of land that is (are) subject to development. For road projects, or utility projects in the right-of-way, the length of the project site and the right-of-way boundaries define the site. Note that drainage impacts are generally assessed for the "project site", under separate definition. Slope. The degree of deviation of a surface from the horizontal; measured as a numerical ratio, percent, or in degrees. Expressed as a ratio, the first number is the horizontal distance (run) and the second is the vertical distance (rise), as 2:1. A 2:1 slope is a 50 percent slope. Expressed in degrees, the slope is the angle from the horizontal plane, with a 90-degree slope being vertical (maximum) and 45 degrees being a 1:1 or 100 percent slope. Version: September 4 20 5June 2021 Packet Pg. 64 2.4.b Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 7/27 Soil. The unconsolidated mineral and organic material on the intermediate surface of the earth that serves as a natural medium for the growth of land plants. Source control BMPs. A structure or operation that is intended to prevent pollutants from coming into contact with storm water through physical separation of areas or careful management of activities that are sources of pollutants. The SWMMWW separates source control BMPs into two types. Structural source control BMPs are physical, structural, or mechanical devices, or facilities that are intended to prevent pollutants from entering stormwater. Operational Source Control BMPs are non-structural practices that prevent or reduce pollutants from entering stormwater. See Volume IV of the SWMMWW for details. Stormwater facility. A constructed component of a stormwater drainage system, designed and constructed to perform a particular function or multiple functions. Stormwater facilities include, but are not limited to, pipes, swales, ditches, culverts, street gutters, detention ponds, retention ponds, constructed wetlands, infiltration devices, catch basins, oil/water separators, and biofiltration swales. Stormwater Management Manual for Western Washington (SWMMWW). The Washington State Department of Ecology's 24Q�2019(as ri,orao�' ^` Stormwater Management Manual for Western Washington. Referred to as the 20142019 SWMMWW. Stormwater site plan. The comprehensive report containing all of the technical information and analysis necessary for regulatory agencies to evaluate a proposed development project for compliance with stormwater requirements. Contents of the Stormwater Site Plan will vary with the type and size of the project, and individual site characteristics. It includes a Construction Stormwater Pollution Prevention Plan (Construction SWPPP) and a Permanent Stormwater Control Plan (PSC Plan). Guidance on preparing a Stormwater Site Plan is contained in Chapter 3 of Volume I of the SWMMWW. Stormwater Treatment and Flow Control BMPs/Facilities. Detention facilities, treatment BMPs/facilities, bioretention, vegetated roofs, and permeable pavements that help meet Minimum Requirements No.6 (Treatment), Minimum Requirement No.7 (Flow Control), or both as described in ECDC 18.30.060. Threshold discharge area. An on site area within a project site that drains to either -draining to a single natural discharge location or multiple natural discharge locations that combine within one -quarter mile downstream (as determined by the shortest flowpath). The examples min Figure 4971: Example TDA Delineations below, - presented in Volume 1 of the c.x"MN43A AI illustrate this definition. The purpose of this definition is to clarify how the thresholds of this code are applied to project sites with multiple discharge points. Version: September 4 20 5June 2021 Packet Pg. 65 Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 8/27 Example of a Site with a Example of a Site with Example of a Site with Single Natural Discharge Multiple Natural Multiple Natural Discharges and a Single Threshold Discharges and a Single and Multiple Threshold Discharge Area Threshold Discharge Area Discharge Areas Natural � -.Natural Natural Natural Natural schar _ atge- ..- Discha" ---fischarge - ---• ` ..- 'bischaiq�.4- Disehp-W Area Area 1 Area 2 Area I Area 2 THRESHOLD �' ... HOLD HRESIIOLD THRESHOLD ENSCHARGE ........"""JHRE �15C ,4RG�-�-'--,;'� "- DISCHARGE D15CHAf�U� -- AREA-- a4 '.,A Elrr AREA ik rA7EA 2 (Shaded} , edj (shad) f Natural~ Natural i Natural r' Discharge Discharge i Discharge Location LocAon i Location - 1 1 l ! >, 1 � ` Y4 Mife Downstream ._-------------- (shortest flow nath) } ` ----------__� _ »� w m c m 0 I M 00 U C U W I m r C d E z c� t0 r a E M a Version: September 4 2015June 2021 Packet Pg. 66 Edmonds Chapter 18.30 STORM WATER MANAGEMENT Figure 1: Example TDA Delineations 2.4.b Page 9/27 Example of a Project Site Example of a Project Site Example of a Project Site with with a single natural with multiple natural multiple natural discharges and discharge and a single TDA discharges and a single TDA multiple TDAs ' .._.�'--- Jy ,TDA - TDA Single - TDA 2 Natural r Natural J 1 Natural discharge Greater than location discharge discharge 1I4 mile locations 114 milelocations r ` 114 miles f 1/4 mile i i Example of a road project with multiple d1wharge points and a single TDA o mBecause the right -most discharge . connecls to the other two discharge flow �I roadway crown paths within I mite, all areas are �i connected as one TDA. Discharge 114 mde 114 mile location — - 114 mile -. c S 3 / Example of a road project with multiple ` / discharge points and multiple TDAs. 4 !C Note: Shaded areas represent - Discharge 11+i mle the limits of the location project site. 11 4 NOT TO SCALE Example TDA Delineations DEPARTMENT OF Revised March 2018 ECOLOGYPlease see http.IA+vwwecyy wa.govloopyright htmf for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. to d C N 0 I M 06 U 0 U W I m C N E t v R r r Q t v a Version: September ,82813June2021 Packet Pg. 67 Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 10/27 Vehicular Use. Regular use of an impervious or pervious surface by motor vehicles. The following are subject to regular vehicular use: roads, un-vegetated road shoulders, bike lanes within the traveled lane of a roadway, driveways, parking lots, unrestricted access fire lanes, vehicular equipment storage yards, and airport runways. The following are not considered subject to regular vehicular use: sidewalks not subject to drainage from roads for motor vehicles, paved bicycle pathways separated from and not subject to drainage from roads for motor vehicles, restricted access fire lanes, and infrequently used maintenance access roads. Waterbody. Surface waters including rivers, streams, lakes, marine waters, estuaries, and wetlands. Waters of the state. Includes those waters defined as "waters of the United States" in 40 CFR Subpart 122.2 within the geographic boundaries of Washington State, and "waters of the state" as defined in Chapter 90.48 RCW which includes lakes, rivers, ponds, streams, inland waters, underground waters, salt waters and all other surface waters and water courses within the jurisdiction of the state of Washington. Wetlands. As defined in ECDC 23.40.005. [Ord. 4026 § 1 (Att. A), 2016]. 18.30.020 Authority and Regulation. A. The Public Works and Utilities Director shall administer this chapter and shall be referred to as the Director. B. The Director shall have the authority to develop, implement, and enforce policies and procedures to administer and enforce this chapter per ECDC 18.30.110 and 18.30.120, such as the Edmonds Stormwater Addendum. C. The requirements of this chapter are minimum requirements. They do not replace, repeal, abrogate, supersede, or affect any other more stringent requirements, rules, regulations, covenants, standards, or restrictions. Where this chapter imposes requirements that are more protective of human health or the environment than those set forth elsewhere, the provisions of this chapter shall prevail. When this chapter imposes requirements that are less protective of human health or the environment than those set forth elsewhere, the provisions of the more protective requirements shall prevail. D. The Director shall have the authority to impose additional requirements on a project or site to meet the purpose of this chapter based on site -specific factors including, but not limited to, location, soil conditions, slope, and designated use. E. Approvals and permits granted under this chapter are not waivers of the requirements of any other laws, nor do they indicate compliance with any other laws. Compliance is still required with all applicable federal, state and local laws and regulations, including rules promulgated under authority of this chapter. F. Compliance with the provisions of this chapter does not necessarily mitigate all impacts to the environment. Thus, compliance with this chapter should not be construed as mitigating all drainage water or other environmental impacts, and additional mitigation may be required to protect the environment pursuant to other applicable laws and regulations. The primary obligation for compliance with this chapter and for preventing environmental harm on or from property is placed upon the applicant. [Ord. 3792 § 1, 2010]. 18.30.030 Applicability. A. This chapter applies to applications_ 1_-sSubmitted on or after January 1, 244-'-2022, and 2_ pplieatiens-sSubmitted prior to January 1, 2017, which have not started construction by January 1, 2022, and 4-3. Submitted prior to January 1, 2022, which have not started construction by July 1, 2027. Version: September 4 20 5June 2021 Packet Pg. 68 Edmonds Page 11/27 Chapter 18.30 STORM WATER MANAGEMENT B. This chapter applies to the following actions on sites that discharge to the City's MS4 or discharges to waters of the state whether or not a City -issued permit is required: 1. Land -disturbing activity, or 2. Creation of new hard surfaces, or 3. Replacement of existing hard surfaces, or 4. Conversion of pervious surfaces, or 5. New connections to the City's MS4, or 6. Any other actions that can increase the volume or rate of stormwater runoff, or cause the generation of pollutants, from the site. 18.30.040 Exemptions. A. Full Exemptions. The following land uses and land -disturbing activities are exempt from the provisions of this chapter: 1. Forest practices regulated under WAC Title 222, except for Class IV general forest practices that are conversions from timberland to other uses, are exempt from the provisions of the minimum requirements. 2. Commercial agriculture practices that involve working land for production are generally exempt. However, land conversion from timberland to agriculture and the construction of impervious surfaces are not exempt. 3. Construction of drilling sites, waste management pits, and associated access roads, and construction of transportation and treatment infrastructure such as pipelines, natural gas treatment plants, natural gas pipeline compressor stations, and crude oil pumping stations are exempt. Operators are encouraged to implement and maintain best management practices to minimize erosion and control sediment during and after construction activities to help ensure protection of surface water quality during storm events. 4. The following pavement maintenance practices or activities are exempt: pothole and square -cut patching, overlaying existing asphalt or concrete pavement with asphalt or concrete without expanding the area of coverage, shoulder grading, reshaping/regrading drainage systems, crack sealing, resurfacing with in -kind material without expanding the road prism, pavement preservation activities that do not expand the road prism, and vegetation maintenance. B. Partial Exemptions. The following land uses and land -disturbing activities are partially exempt from the provisions of this chapter: 1Underground utility projects that replace the ground surface with in -kind material or materials with similar runoff characteristics are only subject to Minimum Requirement No. 2, Construction Stormwater Pollution Prevention. a. Utility instillation as part of a development project, whether in the right-of-way or on private property, are not considered an underground utility_ project for the sake of this partial exemption. 2. The following pavement maintenance practices or activities are considered development, and therefore are not categorically exempt. . a. Removing and replacing a paved surface to base course or a lower level, or repairing the pavement base: if impervious suffaces are not expanded, Minimm Requirements No. 1 No. 5 apply when the thfesholds identified for development projeets in ECDC 19.30.060 are met. Where appropriate, project Version: September 4 20 5June 2021 Packet Pg. 69 Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 12/27 proponents are eneouraged to look for opportunities to use permeable and porous pavements, These are considered replaced hard surfaces. b. Extending the pavement edge without increasing the size of the road prism or paving graveled shoulders: these are considered new shard surfaces and are subjeet to the mini ..w requirements that are triggered when the thresholds identified for developmen4 projeets in ECDC 183n 060 are me c. Resurfacing by upgrading from dirt to gravel, asphalt, or concrete; or upgrading from gravel to asphalt or concrete; or upgrading from a bituminous surface treatment ("chip seal") to asphalt or concrete: these are considered new imper hard surfaces and afe ubje t to the milliffFamor.s tha4 afe triggered when the thfeshelds idewified fer develepment pr-ejeets in ECDC 18.30.060 are met.. 18.30.050 Administration. A. Application, Submittals, and Review. 1. The Director shall review all plans and all other submittals required by ECDC 18.30.050.A.3 for compliance with this chapter when: a. An application for a City permit is required under all other chapters of ECDC Title 18 or 19, or b. A subdivision application is submitted per ECDC 20.75.040. 2. In all other situations when actions under ECDC 18.30.030 apply to a project site, review shall be under a Stormwater permit. 3. All stormwater review submittals shall contain, in addition to the information required under any other applicable City code, a Stormwater Site Plan as described in the Edmonds Stormwater Addendum (see ECDC 18.30.060) and any other information required by the Director. B. Inspections. 1. The Director shall inspect projects at various stages of the work to determine if they comply with the requirements of this chapter, and enforcement actions shall be taken as necessary. These inspections will include, but not be limited to, the following: a. Prior to site clearing and construction to assess site erosion potential, and b. During construction to verify proper installation and maintenance of required erosion and sediment controls and other approved plan components, and c. All permanent stormwater treatment and flow control BMPs/facilities and catch basins in new residential developments every six months until 90 percent of the lots are constructed (or when construction is stopped and the site is fully stabilized) to identify maintenance needs and enforce compliance with maintenance standards as needed, and d. Upon completion of construction and prior to final approval to ensure proper installation of permanent Stormwater control facilities and verify that a maintenance plan is completed and responsibility for maintenance is assigned for stormwater treatment and flow control BMPs/facilities, and e. Post -Construction inspections per ECDC 18.30.090. Version: September 4 20 5June 2021 Packet Pg. 70 Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 13/27 2. When reasonably required by the Director to accomplish the purpose of this chapter or to comply with local, state or federal law or regulation on stormwater, special inspection or testing shall be performed by the applicant. C. Fees. Application, review and inspection fees as set in ECDC Chapter 15.00 shall be paid. 18.30.060 Requirements. A. Documents. The sources of the stormwater management requirements for the City are from the following documents: 1. Western Washington Phase II Municipal Stormwater Permit, Appendix 1, modification date january 16, 2044August 1, 2019 2. 2414 2019 Stormwater Management Manual for Western Washington (SWMMWW) 3. The Edmonds Stormwater Addendum In the event of conflicts between the various provisions, the more stringent provision shall apply. B. Illicit Discharges and Connections. Non-stormwater illicit discharges, including spills, into the MS4, groundwaters, or a water body from any developed or undeveloped lands are prohibited per ECDC Chapter 7.200. C. Thresholds and Applicability 1. The thresholds outlined in this section are only applicable to ECDC 18.30.060.C. See also the Edmonds Stormwater Addendum for supplemental information on thresholds. a. All development shall be required to comply with Minimum Requirement No. 2. b. Category 1 project sites shall comply with Minimum Requirements No. 1 through No. 5. Category 1 includes projects that: i. Result in 2,000 square feet, or greater, of new plus replaced hard surface area, or ii. Have land disturbing activity of 7,000 square feet or greater. c. Category 2 project sites shall comply with Minimum Requirements No. 1 through No. 9. Category 2 includes projects that: i. Result in 5,000 square feet, or greater, of new plus replaced hard surface area, or ii. Convert 0.75 acres, or more, of vegetation to lawn or landscaped areas, or iii. Convert 2.5 acres, or more, of native vegetation to pasture. 2. Additional Requirements for road -related projects. For road -related projects, runoff from the new and replaced hard surfaces (including pavement, shoulders, curbs, and sidewalks) and the converted vegetation areas shall meet all the minimum requirements only if the new hard surfaces total 5,000 square feet or more and total 50 percent or more of the existing hard surfaces within the project limits. Otherwise, the minimum requirements only apply to the new hard surfaces and the converted vegetation areas that exceed the thresholds in (1) above. The project limits shall be defined by the length of the project and the width of the right-of-way. 3New Connections to the City's MS4 when the proposed connection does not involve activity that meets the definition of development. Sites that are not currently connected to the City's MS4 but that wish to connect directly or indirectly to the City's MS4 may be allowed on a case -by -case basis, subject to City approval. For sites that propose to drain greater than or equal to 2,000 square feet of hard surface area to the City's MS4, the project shall comply with the requirement of this chapter, treating all hard surfaces to be drained to the City system as new hard surfaces, unless applicant can demonstrate that the site will discharge in the same manner and quantities prior to the proposed project. Applicant shall account for natural dispersion and/or infiltration which may be occurring if these new hard surfaces area currently drain through pervious areas. Version: September 4 20 5June 2021 Packet Pg. 71 Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 14/27 treatment (such as those outlined in ECDC 18.30.060.D [1] th ough [91) may be required if the conneeti poses any risk to downstream systems such as erosion, flooding, property damage, habitat damage, water— qualitydegradation, or- athef Felated wets. -34. Minimum Requirements may be met for an equivalent (flow and pollution characteristics) area. The equivalent area may be within the same TDA. If the equivalent area is outside the TDA, or off -site, the equivalent area must drain to the same receiving water and the guidance for equivalent facilities using in_ basin transfers must be followed, as detailed in Appendix D of Volume 1 of SWMMWW. D. Minimum Technical Requirements. This section describes the minimum technical requirements for stormwater management at development sites. 1. Minimum Requirement No. 1 — Preparation of Stormwater Site Plans The City shall require a Stormwater Site Plan from all projects meeting the thresholds in ECDC 18.30.060.C. Stormwater Site Plans shall use site -appropriate development principles to retain native vegetation and minimize impervious surfaces to the extent feasible. Stormwater Site Plans shall be prepared in accordance with Chapter 3 of Volume 1 of the SWMMWW and the requirements in the Edmonds Stormwater Addendum. 2. Minimum Requirement No. 2 — Construction Stormwater Pollution Prevention Plan (SWPPP) a. Thresholds: i. All development projects are responsible for preventing erosion and discharge of sediment and other pollutants into receiving waters. Compliance with this minimum requirement can be achieved for an individual site if the site is covered under Ecology's General NPDES Permit for Stormwater Discharges Associated with Construction Activities and fully implementing the requirements of that permit. ii. A Construction SWPPP is required for all projects which a) result in 2,000 square feet or more of new plus replaced hard surface area, b) where a structure with an exterior hard surface area of at least 2,000 square feet is being demolished, c) which disturb 7,000 square feet or more of land, or d) when the site falls within the Earth Subsidence Landslide Hazard Area, Landslide Hazard Area or steep slope critical area. Projects that do not meet any of the above criteria are not required to prepare a Construction SWPPP, but must consider all of the elements listed below for Construction SWPPPs and develop controls for all Construction SWPPP elements that pertain to the project site. b. General Requirements: The SWPPP shall include a narrative and drawings. All BMPs shall be clearly referenced in the narrative and marked on the drawings. The SWPPP narrative shall include documentation to explain and justify the pollution prevention decisions made for the project. Each of the thirteen elements referenced below must be considered and included in the SWPPP unless site conditions render the element unnecessary and the exemption from that element is clearly justified in the narrative of the SWPPP. ii. Clearing and grading activities for developments shall be permitted only if conducted pursuant to an approved site development plan (e.g., building permit, subdivision approval) that establishes permitted areas of clearing, grading, cutting, and filling. These permitted clearing and grading areas and any other areas required to preserve critical or sensitive areas, buffers, native growth protection easements, or tree retention areas as required by the City, shall be delineated on the site plans and the development site. iii. The SWPPP shall be implemented beginning with initial land disturbance and until final stabilization. Sediment and Erosion control BMPs shall be consistent with the BMPs contained in Chapter 4 of Volume II of the SWMMWW. Version: September 4 20 5June 2021 Packet Pg. 72 Edmonds Chapter 18.30 STORM WATER MANAGEMENT c. Seasonal Work Limitations: Page 15/27 From October 1 through April 30, clearing, grading, and other soil disturbing activities may only be authorized by the City if it can be demonstrated that silt -laden runoff will be prevented from leaving the site through a combination of the following: Site conditions including existing vegetative coverage, slope, soil type, and proximity to receiving waters; and ii. Limitations on activities and the extent of disturbed areas; and iii. Proposed erosion and sediment control measures, in accordance with ECDC 18.30.060.D.2.d below. Based on the information provided and/or local weather conditions, the City may expand or restrict the seasonal limitation on site disturbance. The following activities are exempt from the seasonal clearing and grading limitations, except for sites lying in whole or in part within an earth subsidence and landslide hazard area as defined by ECDC 19.10.020.F: Routine maintenance and necessary repair of erosion and sediment control BMPs, ii. Routine maintenance of public facilities or existing utility structures that do not expose the soil or result in the removal of the vegetative cover to soil, and iii. Activities where there is one hundred percent infiltration of surface water runoff within the site in approved and installed erosion and sediment control facilities. d. Construction SWPPP Elements Construction SWPPP elements are required in accordance with Chapter 23, Section 2'-5.23.4.2 of Volume I of the SWMMWW and the requirements in the Edmonds Stormwater Addendum. 3. Minimum Requirement No. 3 — Source Control of Pollution All known, available and reasonable source control BMPs must be required for all projects approved by the City. Source control BMPs must be selected, designed, and maintained in accordance with Volume IV of the SWMMWW. All single family residential projects shall, at a minimum, incorporate required BMPs from SWMMWW Volume IV, S411 — BMPs for Landscaping and Lawn/Vegetation Management. 4. Minimum Requirement No. 4 — Preservation of Natural Drainage Systems and Outfalls Natural drainage patterns shall be maintained, and discharges from the project site shall occur at the natural location, to the maximum extent practicable. The manner by which runoff is discharged from the project site must not cause a significant adverse impact to downstream receiving waters and down gradient properties. The discharge must have an identified overflow route that is safe and certain, and leads to the ultimate outfa111ocation (such as a receiving water or municipal drainage system). All outfalls require energy dissipation. To demonstrate compliance with this core requirement, all projects shall submit an off -site qualitative analysis. If an existing problem (or potential future problem after development) is identified, mitigation will be required to prevent worsening of that problem. A quantitative analysis may be required for any project deemed to need additional information or where the project proponent or the City determines that a quantitative analysis is necessary to evaluate the off -site impacts or the capacity of the conveyance system. See the Edmonds Stormwater Addendum for additional details on complying with this requirement. 5. Minimum Requirement No. 5 — On -site Stormwater Management Version: September 4 20 5June 2021 Packet Pg. 73 Edmonds Chapter 18.30 STORM WATER MANAGEMENT a. Applicability: Page 16/27 On -site Stormwater Management BMPs are required in accordance with the following project thresholds, standards, and lists to infiltrate, disperse, and retain stormwater runoff on -site to the extent feasible without causing flooding or erosion impacts. See the SWMMWW and the Edmonds Stormwater Addendum for additional details on On -site Stormwater Management BMP infeasibility. b. Project Thresholds: There are five project scenarios outlined below that determine the applicability of Minimum Requirement No. 5 — On -site Stormwater Management. The first four scenarios apply to projects that discharge directly or indirectly to the City's MS4. The fifth scenario applies to project discharges that do not enter the City's MS4. Note that more than one of the five scenarios may apply to a given proj ect: Retrofit. Projects that discharge directly or indirectly to the City's MS4 and that contain existing hard surfaces on the parcel or common plan of development that do not drain to an approved stormwater management facility are required to provide On -site Stormwater Management BMPs to manage a portion of those existing hard surfaces that will remain after project completion. BMPs from List No.l (See ECDC 18.30.060.D.5.d) shall be applied to a minimum of 25 percent of those existing unmanaged surfaces, but to no more than the area equal to the proposed new plus replaced hard surfaces. Within the Perrinville Creek basin, the retrofit value shall be increased from 25% to 50%. Only for those existing unmanaged hard surfaces that remain after project completion, applicants are not required to evaluate BMPs in priority order or document infeasibility for these existing surfaces (as is required under ECDC 18.30.060.D.5.b [ii] and [iii] below). However, if it is determined that the minimum percentage requirement cannot be met due to BMP infeasibility, documentation of BMP infeasibility is required. In addition, when runoff from exiting -unmanaged hard surfaces is mixed with runoff from new plus Fepla eamanaged hard surfaces, those BMPs must be selected and designed i-n- -dan e witl the 0 epAs for- maaagem&4 ofnewplus -epl ee for all areas which contribute runoff to the BMPna� (per sections [ii] and [iii] below). See the SWMMWW and the Edmonds Stormwater Addendum for additional details on On -site Stormwater Management BMP infeasibility. This requirement is specific to minimum requirement #5 only. The surfaces treated by this requirement do no need to be added to project thresholds or mitigated under other minimum requirements. Impervious surfaces disturbed solely for installation of BMPs proposed to satisfy this requirement need not be consider as replaced hard surfaces for the project. ii. Category 1. Category 1 project sites that discharge directly or indirectly to the City's MS4 and are required to comply with Minimum Requirements No. 1 through No. 5 (per ECDC 18.30.060.C) shall either: a. Use On -site Stormwater Management BMPs from List No.l for all new plus replaced hard surfaces and land disturbed (See ECDC 18.30.060.D.5.d); or b. Demonstrate compliance with the LID Performance Standard (See ECDC 18.30.060.D.5.c). Projects selecting this option cannot use rain gardens. They may choose to use bioretention BMPs as described in the SWMMWW. iii. Category 2. Category 2 project sites that discharge directly or indirectly to the City's MS4 and are required to comply with Minimum Requirements No. 1 through No. 9 (per ECDC 18.30.060.C) shall either: Version: September 8, 20 5June 2021 Packet Pg. 74 Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 17/27 a. Use On -site Stormwater Management BMPs from List No.2 for all new plus replaced hard surfaces and land disturbed (See ECDC 18.30.060.D.5.e); or b. Demonstrate compliance with the LID Performance Standard (See ECDC 18.30.060.D.5.c). Projects selecting this option cannot use rain gardens. They may choose to use bioretention BMPs as described in the SWMMWW. iv. Direct Discharge Requirement. Projects that discharge directly to Puget Sound through the City's MS4 (in accordance with the restrictions applicable to direct discharges to Puget Sound presented in Section2-.5-.73.4.7 of Volume I of the SWMMWW) do not have to achieve the LID Performance Standard, nor consider bioretention, rain gardens, permeable pavement, or full dispersion, but must meet the following: a. Projects must implement BMP T5.13 (Post -Construction Soil Quality & Depth); BMPs T5. l0A Downspout Full Infiltration Systems, TS.IOB Downspout Dispersion Systems, or T5.1 OB Perforated Stub -out Connections; and BMP T5.11 Concentrated Flow Dispersion or T5.12 Sheet Flow Dispersion; if feasible for all new plus replaced hard surfaces and land disturbed. See the SWMMWW and the Edmonds Stormwater Addendum for additional details on On -site Stormwater Management BMP infeasibility V. Projects that do not drain directly or indirectly to the City's MS4 are required to implement one of the following: a. Project sites may discharge to the downstream private property (e.g., projects located above BNSF property) with approval from the downstream property owner(s). b. Project sites may discharge runoff to an on -site system. For sites located within earth subsidence and landslide hazard areas or their buffers, a geotechnical design, analysis, and report by a geotechnical engineer is required for the on -site system. On -site Stormwater Management BMPs from List No.1 in ECDC 18.30.060.D.5.d shall be evaluated for all new plus replaced hard surfaces and land disturbed. Projects are not required to evaluate BMPs in priority order or document infeasibility. The project applicant may be subject to an extra permit processing fee for City review of the geotechnical analysis. Projects are required to comply with all other applicable City requirements, such as ECDC 19.10 (earth subsidence and landslide hazard areas). ii. For sites located outside earth subsidence and landslide hazard areas or their buffers, ECDC 18.30.060.D.5.ii and ECDC 18.30.060.D.5.iii shall be followed to evaluate site appropriate BMP's. c_Subject to prior approval by the City, project sites may pump on -site runoff to the City's MS4. A quantitative downstream analysis in accordance with Minimum Requirement No. 4 and the Edmonds Stormwater Addendum will be required. If the City's MS4 does not have adequate capacity to receive the applicant's pumped flows, the applicant is required to install an on -site detention system to store runoff and pump it to the MS4 at an approved rate. Version: September 4 20 5June 2021 Packet Pg. 75 Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 18/27 vi. Projects under 2,000 SF of new plus replaced hard surfaces which discharge to an existing BMP with a surfaces overflow, shall expand the BMP size for the proposed new plus replaced hard surfaces based on existing design data. Alternatively, or where existing design data can not be found, the project shall discharge to a separate system appropriate sized per the designer. c. LID Performance Standard For projects that elect to meet the LID Performance Standard to comply with ECDC 18.30.060.D.b (ii) and (iii), Stormwater discharges shall match developed discharge durations to pre -developed durations for the range of pre -developed discharge rates from 8 percent of the 2-year peak flow to 50 percent of the 2-year peak flow from the project site. Refer to the Standard Flow Control Requirement section in Minimum Requirement No. 7 for information about the assignment of the pre -developed condition. Project sites that must also meet Minimum Requirement No. 7 shall match flow durations between 8 percent of the 2-year flow through the full 50-year flow. Projects meeting the LID performance criteria are still required to comply with the requirements for BMP T5.13: Post -Construction Soils Quality and Depth, to the maximum extent feasible. d. List No.I for Category 1 project sites: On -site Stormwater Management BMPs for Projects Triggering Minimum Requirements No. 1 through No. 5. For projects that elect to use List No. 1 to comply with ECDC 18.30.060.D.b (ii), for each surface, consider the BMPs in the order listed for that type of surface. Use the first BMP that is considered feasible. No other On -site Stormwater Management BMP is necessary for that surface. Feasibility shall be determined by evaluation against design criteria, limitations, and infeasibility criteria identified for each BMP in the SWMMWW and the Edmonds Stormwater Addendum; and Competing Needs Criteria listed in Chapter 5-3 of Volume V-I of the SWMMWW. Lawn and landscaped areas: Post -Construction Soil Quality and Depth in accordance with BMP T5.13 in Chapter 5 of Volume V of the SWMMWW. Roofs: i. Full Dispersion in accordance with BMP T5.30 in Q Volume V of the SWMMWW_ 40 i-. ii. -Downspout Full Infiltration Systems in accordance with BMP T5.I OA in Seetie ff 3.1 .' 4 Volume ITV of the SWMMWW. ii,iii. Rain Gardens in accordance with BMP T5.14A in Chapter 5 of Vowme V, or Bioretention in accordance with Chapter-7BMP T7.30 of Volume V of the SWMMWW. The rain garden or bioretention facility must have a minimum horizontal projected surface area below the overflow which is at least 5 percent of the area draining to it. ii-.iv. Downspout Dispersion Systems in accordance with BMP T5.1 OB in Seetie 3.' .2 of -Volume ITV of the SWMMWW. V. Detention vaults or pipes in accordance with the Edmonds Stormwater Addendum 6.3. iv-.vi. Perforated Stub -out Connections in accordance with BMP T5.1OC in Seel on 3.1.3 of Volume ITV of the SWMMWW. Version: September 4 20 5June 2021 Packet Pg. 76 Edmonds Chapter 18.30 STORM WATER MANAGEMENT Other Hard Surfaces: Full Dispersion in accordance with BMP T5.30 in 0h Volume V of the SWMMWW. Page 19/27 ii. Full infiltration for equivalent surfaces areas per BMP T5.10A and/or Permeable Pavement in accordance with BMP T5.15 in r'���_5-&f-Volume V of the SWMMWW, or ii-.iii. Rain Gardens in accordance with BMP T5.14 ^ i Chapter 5 of Vo me V, _or Bioretention in accordance with BMP T7.30Ghapter- 7 of Volume V of the SWMMWW. The rain garden or bioretention facility must have a minimum horizontal projected surface area below the overflow which is at least 5 percent of the area draining to it. iii-.iv. Sheet Flow Dispersion in accordance with BMP T5.12, or Concentrated Flow Dispersion in accordance with BMP T5.11 in 0h of -Volume V of the SWMMWW. iY-. v. Detention vaults or pipes in accordance with the Edmonds Stormwater Addendum 6.3. TheCity may waive the r-e"ir-emeat to install a deten4ion vauit if the dewfistr-eafn analysis ifl Minimum Re"ifemefft #4, or available City data, indieme that peak flew eefAfel is not - e. List No.2 for Category 2 project sites: On -site Stormwater Management BMPs for Projects Triggering Minimum Requirements No. 1 through No. 9. For projects that elect to use List No. 2 to comply with ECDC 18.30.060.D.b (iii), for each surface, consider the BMPs in the order listed for that type of surface. Use the first BMP that is considered feasible. No other On -site Stormwater Management BMP is necessary for that surface. Feasibility shall be determined by evaluation against design criteria, limitations, and infeasibility criteria identified for each BMP in the SWMMWW; and Competing Needs Criteria listed in Chapter 5-3 of Volume V-I of the SWMMWW. Lawn and landscaped areas: Post -Construction Soil Quality and Depth in accordance with BMP T5.13 in Chapterf Volume V of the SWMMWW. Roofs: i. Full Dispersion in accordance with BMP T5.30 in Qi Volume V of the SWMMWW_ �.ii. Downspout Full Infiltration Systems in accordance with BMP T5.10A in Seel o 3.' .1 of - Volume ITV of the SWMMWW. iii. Bioretention in accordance with BMP T7.30 of Volume V of the SWMMWW. The rain garden or bioretention facility must have a minimum horizontal projected surface area below the overflow which is at least 5 percent of the area drainingto o it. ii. Bier-etepAiaa (See Chapter 7 ef Volume 3.1 of the SAIMN4WW) f4eilities that have a fnifiiffimum suffaee area draining to it Version: September 4 20 5June 2021 Packet Pg. 77 2.4.b Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 20/27 iii,iv. Downspout Dispersion Systems in accordance with BMP T5.1 OB in Seetion 3.' .2 of -Volume III of the SWMMWW. V. Detention vaults or pipes in accordance with the Edmonds Stormwater Addendum 6.3. iv-.vi. Perforated Stub -out Connections in accordance with BMP T5.1 OC in Section 3.1.3 of Volume III of the SWMMWW. Other Hard Surfaces: Full Dispersion in accordance with BMP T5.30 in Qh Volume V of the SWMMWW. ii. Full infiltration for equivalent surfaces areas per BMP T5.I OA in Volume III of the SWMMWW and/or Permeable pavement in accordance with BMP T5.15 in Ql Volume V of the SWMMWW. iii. Bioretention (See Qt^ 4-Volume V of the SWMMWW) facilities that have a minimum horizontally projected surface area below the overflow which is at least 5 percent of the total surface area draining to it. iv. Sheet Flow Dispersion in accordance with BMP T5.12, or Concentrated Flow Dispersion in accordance with BMP T5.11 in Qh Volume V of the SWMMWW. V. Detention vaults or pipes in accordance with the Edmonds Stormwater Addendum 6.3. Note that if the pr-ojeet is required to construct a flow eent-rol facility to comply with Nii i Requirement No. 7 (per ECDC 19.30.060.D.7), a detention vault is not required to be installed to meet Minimum ReEpairemen4 NE). 5. in addition, the City may waive the FeEtuiremen install a detention vault if the dE),A%st+eam analysis in Minimum Requir-ement #4, or- available f. Overflows: All non -dispersion BMPs sized solely for Minimum Reauirement #5 are anticinated to have an overflow discharge on a semi -regular basis and therefore requires a sub -surface pied connection directly to the MS 4 system. i. In order to eliminate a piped overflow connection, the project shall be designed to infiltrate 100% of the modelled 100-year storm per continuous modeling. A safe and certain surface overflow path must still be provided and may not negatively impact adjacent properties. ii. In cases where the City MS4 is not in a location where a reasonable connection can be made for a project in capable of fully infiltrating per ECDC 18.30.060.D.5.fi above: • Extensions equal to or less than the length of the project frontage would be anticipated and generally not consider for an exception to 18.30.060.D.5.f.i. • Extension exceeding the project frontage length will be considered on a case -by -case basis for exception to 18.30.060.D.5.f.i. 6. Minimum Requirement No. 6 — Runoff Treatment a. Project Thresholds: When assessing road -related projects against the following thresholds, only consider those hard and pervious surfaces that are subject to this minimum requirement per ECDC Version: September 4 20 5June 2021 Packet Pg. 78 2.4.b Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 21/27 18.30.060.C.2. For all other projects, the requirements apply to the new plus replaced hard surfaces and the converted vegetation areas. The following require construction of stormwater treatment facilities: Projects in which the total of pollution -generating hard surface (PGHS) is 5,000 square feet or more in a threshold discharge area of the project, or ii. Projects in which the total of pollution -generating pervious surfaces (PGPS) - not including permeable pavements - is 0.75 acres or more in a threshold discharge area, and from which there will be a surface discharge in a natural or man-made conveyance system from the site. b. Treatment -Type Thresholds and Facility Sizing: Treatment -Type Thresholds in accordance with Step 2 roil C rt-- l) Step n (Pha.,phet%s Treatment), Step 5 (hpAianeed Treatment), and Step 6 (Basie T-reatmeno of Chapter- , Section 2-.41_2, Volume V-III of the SWMMWW. Phosphorus treatment shall be required for projects draining to Hall Creek and Lake Ballinger. ii. Treatment Facility Sizing, including Water Quality Design Storm Volume, Water Quality Design Flow Rate, and Downstream Facilities, of -in accordance with Chapter 2-3, Section ''�63.4.6, Volume I of the SWMMWW. c. Treatment Facility Selection, Design, and Maintenance Stormwater treatment facilities shall be: Selected in accordance with the process identified in Chapter 4-1 of Volume III, and Chapter of Volume Vof the SWMMWW, Designed in accordance with the design criteria in Volume V of the SWMMWW, and iii. Maintained in accordance with the maintenance schedule in Volume V of the SWMMWW d. Additional Requirements The discharge of untreated stormwater from pollution -generating hard surfaces to ground water will not be authorized by the City except for infiltration or dispersion of runoff through BMPs designed and implemented per ECDC 18.30 and SWMMWW. All asseeiate - rep n+Ust be treated using On site Ster-mwater- MaftagemepA BN4Ps designed to pr-evide the r-equired level of or- by ififiltfatieff through soils meeting the sail suitability eriteria in Chapter- 3 of Volume U! of the cWrnW. Minimum Requirement No. 7 - Flow Control aApplicability: Flow control is required on projects meeting the thresholds summarized below to reduce the impacts of stormwater runoff from hard surfaces and land cover conversions. Flow control in accordance with Minimum Requirement No. 7 is not required for projects that discharge directly to, or indirectly through the City's MS4 to Puget Sound subject to the restrictions of the TDA Exemption (aka. direct discharge exemption) per SWMMWW Section 3.4.7 of Volume I - (other minimum requirements may still apply). See ECDC 18.30.060.D.5.b.iv and Section -2-.53_4.7 of Volume I of the SWMMWW for additional restrictions applicable to direct discharges to Puget Sound. If the discharge drains to a stream that leads to a wetland, or to a wetland that has an outflow to a stream, both this minimum requirement (Minimum Requirement No. 7) and Minimum Requirement No. 8 apply. Version: September 4 20 5June 2021 Packet Pg. 79 Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 22/27 a-.b_Thresholds: When assessing road -related projects against the following thresholds, only consider only those impervious, hard, and pervious surfaces that are subject to this minimum requirement per ECDC 18.30.060.C.2. For all other projects, the requirements apply to the new plus replaced hard surfaces and the converted vegetation areas. The following circumstances require achievement of the standard flow control requirement for western Washington: Projects in which the total of effective impervious surfaces is 10,000 square feet or more in a threshold discharge area, or ii. Projects that convert 0.75 acres or more of vegetation to lawn or landscape, or convert 2.5 acres or more of native vegetation to pasture in a threshold discharge area, and from which there is a surface discharge in a natural or man-made conveyance system from the site, or iii. Projects that through a combination of hard surfaces and converted vegetation areas cause a 0.10 cubic feet per second (cfs) increase or greater in the 100-year flow frequency from a threshold discharge area as estimated using the Western Washington Hydrology Model or other approved model and one -hour time steps (or a 0.15 cfs increase or greater using 15- minute time steps). b:c_Standard Flow Control Requirement (applies to discharges directly or indirectly to the City's MS4, except for projects that meet the direct discharge requirements outlined in "a" above and/or projects discharging to Perrinville Creek): Stormwater discharges shall match developed discharge durations to pre -developed durations for the range of pre -developed discharge rates from 50 percent of the 2-year peak flow up to the full 50-year peak flow. The pre -developed condition to be matched shall be a forested land cover unless reasonable, historic information is available that indicates the site was prairie prior to settlement (modeled as "pasture" in the Western Washington Hydrology Model). This standard requirement is waived for sites that will reliably infiltrate all the runoff from hard surfaces and converted vegetation areas. d. Perrinville Basin Flow Control Standard (applies to all discharges within the Perrinville Creek basin)_ shall be an elevated level of flow control design. Discharges to the Perrinville Creek Basin shall maintain the durations of high flows at their predevelopment levels for all flows greater than one-half of the 2-year flow up to the 50-year flow AND holding the 100-year peak flow rate at its predevelopment level. The predevelopment peak flow rates for the 2-year and 10-year runoff events are also intended to be maintained. ce_Additional Requirement: Flow Control BMPs shall be selected, designed, and maintained in accordance with Volume III of the SWMMWW or an approved equivalent. 8. Minimum Requirement No. 8 — Wetlands Protection a. Applicability: The requirements below apply only to projects whose stormwater discharges into a wetland, either directly or indirectly through a conveyance system. b. Thresholds: The thresholds identified in Minimum Requirement No. 6 — Runoff Treatment, and Minimum Requirement No. 7 — Flow Control shall also be applied to determine the applicability of this requirement to discharges to wetlands. c. Standard Requirement: Projects shall comply with Guide Sheets No. 1 through No. 3 in Appendix I-D of the SWMMWW. The hydrologic analysis shall use the existing land cover condition to determine the existing hydrologic conditions unless directed otherwise by a regulatory agency with jurisdiction. d. Additional Requirements: Stormwater treatment and flow control facilities shall not be built within a natural vegetated buffer, except for: Necessary conveyance systems as approved by the City; or Version: September 8, 20 5June 2021 Packet Pg. 80 2.4.b Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 23/27 ii. As allowed in wetlands approved for hydrologic modification or treatment in accordance with Guide Sheet 2 in Appendix I-D of the SWMMWW. An adopted and implemented basin plan prepared in accordance with the provisions of Section 7 of Appendix 1 of the Phase II NPDES Municipal Stormwater Permit. 9. Minimum Requirement No. 9 — Operation and Maintenance An operation and maintenance manual that is consistent with the provisions in Volume I and Volume V of the SWMMWW is required for proposed Stormwater Treatment and Flow Control BMPs/facilities. The party (or parties) responsible for maintenance and operation shall be identified in the operation and maintenance manual. For private facilities approved by the City, a copy of the operation and maintenance manual shall be retained on -site or within reasonable access to the site, and shall be transferred with the property to the new owner. For public facilities, a copy of the operation and maintenance manual shall be retained in the appropriate department. A log of maintenance activity that indicates what actions were taken shall be kept and be available for inspection. 18.30.070 Exceptions, Adjustments, and Appeals. A. Exceptions. 1. The Director may approve a request for an exception to the minimum requirements of this chapter following legal public notice of an application for an exception and of the Director's decision on the application. All legal public notice related to this request for an exception shall be in the manner prescribed in ECDC 20.03.002 and the applicant shall pay all costs to publish the legal public notices required by this provision. The Director shall provide and keep written findings of fact of the decision. 2. The approval of the exception shall only be granted when the applicant demonstrates that the requirement would cause a severe and unexpected economic hardship. To determine whether the requirement imposes a severe and unexpected economic hardship on the project applicant, the applicant must document for City review and approval, all of the following, at a minimum: a. The current, pre -project use of the site; and b. How application of the requirement(s) for which an exception is being requested restricts the proposed use of the site compared to the restrictions that existed prior to adoption of this chapter; and c. The possible remaining uses of the site if the exception were not granted; and d. The possible uses of the site that would have been allowed prior to the adoption of this chapter; and e. A comparison of the estimated amount and percentage of value loss as a result of the requirements versus the estimated amount and percentage of value loss as a result of requirements that existed prior to adoption of the requirements of this chapter; and f. The feasibility of the applicant to alter the project to apply the requirements of this chapter. 3. Any exception must meet the following criteria: a. The exception will not increase risk to the public health and welfare, nor be injurious to other properties in the vicinity and/or downstream, and to the quality of waters of the state; and b. The exception is the least possible exception that could be granted to comply with the intent of the minimum requirements. 4. An exception to the requirements shall only be granted to the extent necessary to provide relief from the economic hardship as determined by the Director, to alleviate the harm or threat of harm to the degree that Version: September 4 20 5June 2021 Packet Pg. 81 2.4.b Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 24/27 compliance with the requirement becomes technically feasible, or to perform the emergency work that the Director determines is warranted. 5. The Director may require an applicant to provide additional information at the applicant's expense, including (but not limited to) an engineer's report or analysis. 6. When an exception is granted, the Director may impose new or additional requirements to offset or mitigate harm or the threat of harm that may be caused by granting the exception, or that would have been prevented if the exception had not been granted. B. Adjustments. 1. The Director may approve a request for adjustments to the requirements of this chapter when the Director finds that: a. The adjustment provides substantially equivalent environmental protection; and b. The objectives of safety, function, environmental protection, and facility maintenance are met, based on sound engineering practices. During construction, the Director may require, or the applicant may request, that the construction of drainage control facilities and associated project designs be adjusted if physical conditions are discovered on the site that are inconsistent with the assumptions on which the approval was based, including (but not limited to) unexpected soil or water conditions, weather -generated problems, or changes in the design of the improved areas; and A request by the applicant for an adjustment shall be submitted to the Director for review and approval prior to implementation. The request shall be in writing and shall provide facts substantiating the requirements of subsection (C)(1) of this section, and if made during construction, the factors in subsection (C)(2) of this section. Any such modifications made during the construction of drainage control facilities shall be included with the final approved drainage control plan. C. Appeal. 1. The Director's decision on an application for an exception or adjustment may appeal to the hearing examiner in accordance with a Type II appeal process in ECDC Chapter 20.06. 2. The applicant shall carry the burden of proof. 3. The decision of the hearing examiner is appealable to superior court in accordance with Chapter 36.70C RCW. [Ord. 3792 § 1, 2010]. 18.30.080 Access and Covenants. A. Access. Proper ingress and egress shall be provided to the City to inspect or perform any duty imposed upon the City by this Title. The City shall notify the responsible party in writing of a failure to provide access. If the responsible party fails to respond within seven days from the receipt of notification, the City may order the work required to be completed or otherwise address the cause of improper access. The obligation for the payment of all cost that may be incurred or expended by the City in causing such work to be done shall be imposed on the person holding title to the subject property. B. Covenants. Maintenance covenants shall be required for each site/lot that will be maintained by a private entity such as an individual, corporation, or homeowner's association. The maintenance covenant shall address or append requirements and responsibilities for long-term management and maintenance the applicable BMP(s). Maintenance covenants shall be as specified in City Engineering Division documents or approved by the Director, and recorded with Snohomish County and on all proper deeds [Ord. 3792 § 1, 2010]. Version: September 4 20 5June 2021 Packet Pg. 82 2.4.b Edmonds Page 25/27 Chapter 18.30 STORM WATER MANAGEMENT 18.30.090 Post Construction Inspection and Maintenance Roles and Responsibilities. Proper construction inspection and maintenance of stormwater facilities is essential for the protection of the City's MS4 and the environment. A. Stormwater Maintenance and Inspection Standards. Stormwater facilities shall be inspected and maintained per the requirements of Volume I and Volume V of the SWMMWW. For systems which do not have a maintenance standard, the owner shall develop a standard based on guidelines from the manufacturer, designer, or a registered professional engineer and submit the standards to the Director for approval. The purpose of the maintenance standard is to determine if maintenance is required. The maintenance standard is not a measure of the facility's required condition at all times between inspections. Exceeding the maintenance standard between inspections is not a violation of this chapter. B. Ownership. Stormwater facilities are either privately or publicly owned and maintained. All stormwater facilities that serve private property are private, unless an agreement between the property owner and the City states otherwise. Stormwater facilities that are privately owned by a homeowner's association or similar organization also are private. The City may offer an incentive program to owners to support the proper maintenance of private storm drainage facilities. C. Public Stormwater Facilities. The City shall be responsible for operating, maintaining, repairing, and replacing public stormwater facilities as funded through the Stormwater Utility. D. Maintenance and Inspection of Permanent Facilities. All privately owned storm drainage facilities or controls shall be maintained by the owner, or the homeowner or owner association ("owner") if one is established as part of a residential or commercial development. All private storm drainage facilities shall be regularly inspected to ensure proper operation and shall monitor the facility or control as required or as set forth in the SWMMWW. The Owner shall maintain records of inspection and maintenance, disposal receipts, and monitoring results. The records shall catalog the action taken, the person who took it, the date said action was taken, how it was done, and any problems encountered or follow-up actions required. The records shall be made available to the City upon request. The Owner shall maintain a copy of the Stormwater Operations and Maintenance Manual (if required) on site, and shall make reference to such document in real property records filed with Snohomish County, so others who acquire real property served by the privately owned storm drainage facilities or controls are notified of their obligation to maintain such facilities or controls. E. City Inspection of private stormwater facilities. The City shall have the authority to periodically inspect private stormwater facilities, including low impact development stormwater facilities, for compliance with this chapter. F. Right of Entry. An authorized representative of the City may enter private property at all reasonable times to conduct inspections, tests or to carry out other duties imposed by the a state or Federal program provided that the City makes a good faith effort to notify the property owner or person responsible for the premises prior to entering and presents proper credentials to that person. If entry is refused or cannot be obtained, the Director shall have recourse to every remedy provided by law to secure entry, including but not limited to, obtaining an administrative warrant for entry. G. Right of Entry for Illicit Discharge. In the event of an illicit discharge from a privately -owned stormwater facility caused by improper maintenance or operation or other circumstance, the provisions of ECC 7.200 shall apply. H. Maintenance Responsibilities. Upon written notice by the City, a private stormwater facility shall be promptly repaired and/or brought up to applicable standards by the property owner or the person responsible for said facility. If a private stormwater facility serves multiple lots and the responsibility for maintenance has not been specified on a recorded subdivision plat, short plat, or other legal document, maintenance, operation and repair responsibility shall rest with the homeowners' association, if one exists, or otherwise with the properties served by the facility, or finally, with the owners of the property on which the facilities are located. I. Disposal of Waste from Maintenance Activities. Disposal of waste from maintenance activities shall be conducted in accordance with the minimum Functional Standards for Solid Waste Handling, Chapter 173-304 WAC, Version: September 4 20 5June 2021 Packet Pg. 83 Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 26/27 guidelines for disposal of waste materials from storm water maintenance activities, and where appropriate, the Dangerous Waste Regulations, Chapter 173-303 WAC. 18.30.100 Enforcement Procedures. A. General enforcement action shall be in accordance with this chapter whenever a person has violated any provision of this chapter. The choice of enforcement action is at the discretion of the City. B. Civil Penalties Adopted. ECDC Chapter 20.110 enforcement procedures are herein adopted in full, as modified in this chapter, with the proviso that repeat offenders or violations deemed an immediate public hazard shall be subject to compliance and appeal timelines as deemed appropriate by the Director based on the specific nature of the violation. C. Maintenance Orders. The Director shall have the authority to issue to an owner or person an order to maintain or repair a component of a stormwater facility or BMP to bring it into compliance with this chapter, the SWMMWW, the Edmonds Stormwater Addendum, and the Edmonds Community Development Code. The order shall include: 1. A description of the specific nature, extent and time of the violation and the damage or potential damage that reasonably might occur; 2. A notice that the violation or the potential violation cease and desist and, in appropriate cases, the specific corrective actions to be taken; and 3. A reasonable time to comply, depending on the circumstances. D. Civil Penalty. A person who fails to comply with the requirements of this chapter, who fails to conform to an approval or order issued, who undertakes development without first obtaining approval, or who fails to comply with a stop work order issued under these regulations shall be subject to a civil penalty levied in accordance with the provisions of ECDC Chapter 20.110; provided, however, that the appeal process shall commence with a notice of violation as provided in ECDC 20.110.040.13. Civil penalties for code violations shall be imposed in accordance with the provisions of ECDC Chapter 20.110; provided, however, that in addition to the penalties set forth in that chapter, the hearing examiner is authorized to levy a penalty of up to twenty thousand dollars ($20,000) per occurrence based upon an assessment of the following factors. Where such factors are present, the hearing examiner is authorized to levy such penalty after taking into consideration the full impact of the violation and any mitigating circumstances (see subsection (2) below): a. The violation created a risk to public health and the significance of the risk. b. The violation damaged the environment and the significance of the damage. c. The violation caused damage to public and private property and the significance of such damage. d. A history of similar violations, if any. e. The economic benefit of the violations, if any, to the person or entity responsible for the violations. 2. Mitigating circumstances which may be used to offset or reduce the time resulting from the application of the preceding factors are limited to: a. Full compliance with a voluntary compliance agreement and no history of similar violations. b. Full compliance with a voluntary compliance agreement and a history of one or two similar violations (lesser reduction). Version: September 4 20 5June 2021 Packet Pg. 84 2.4.b Edmonds Chapter 18.30 STORM WATER MANAGEMENT Page 27/27 c. A "voluntary compliance agreement" is defined as a legally binding agreement entered into between the City and the alleged violators, by which the violator(s) acknowledge the existence of the violation, waive all appeal rights, and agree to and do pay a fine in an amount stipulated to between the violator and the City. If the violation(s) are not corrected as ordered, or a voluntary compliance agreement is not entered into within that time period and no appeal is filed, the penalty for the next 15-day period shall be 150 percent of the initial penalties, and the penalties for the next 15-day period shall be 200 percent of the initial penalties. The intent of this subsection is to increase penalties beyond the maximum penalties stated as an additional means to achieve timely compliance. Unless otherwise provided in a voluntary compliance agreement, civil penalties shall be paid within 30 days of service of the notice and order or stop work order if not appealed. Payment of the civil penalties assessed under this chapter does not relieve a person found to be responsible for a code violation of his or her duty to correct the violation or to pay any and all civil penalties or other cost assessments issued pursuant to this chapter. The City may suspend immediate payment of civil penalties if the person responsible for a code violation has entered into a voluntary compliance agreement. Penalties shall begin to accrue again pursuant to the terms of the voluntary compliance agreement if any necessary permits applied for are denied, canceled or not pursued, if corrective action identified in the voluntary compliance agreement is not completed as specified, or if the property is allowed to return to a condition similar to that condition which gave rise to the voluntary compliance agreement; provided, however, that additional penalties shall not be imposed until additional notice and opportunity for hearing have been provided in accordance with ECDC Chapter 20.110. Civil penalties assessed create joint and several personal obligations in all persons responsible for a code violation. E. The determination of the hearing examiner issued in accordance with ECDC Chapter 20.110 shall be appealable to the Snohomish County superior court in accordance with the provisions of Chapter 36.70C RCW. F. The remedies provided for in this section shall not be exclusive. The City may also use other civil and administrative remedies available to it, including but not limited to the remedies provided in ECDC Title 19 and the state building and dangerous buildings codes. Version: September 4 20 5June 2021 Packet Pg. 85 2.4.c ADDENDUM TO EDMONDS COMMUNITY DEVELOPMENT CODE CHAPTER 18.30 (EDMONDS STORMWATER ADDENDUM) J October 2021 Packet Pg. 86 2.4.c 0 CM Oo r U a V W d O U r c 0 E 0 tm cv c L d 3 E L O 4- 0 r_ O N L a c a� U I E 7 C d a L d 3 E L O Cl) N C O E W N N N I U r c a) E t v cv r r Q c O E t u 2 Q Packet Pg. 87 OCTOBER 2021 2.4.c EDMONDS STORMWATER ADDENDUM CONTENTS 1 Introduction...............................................................................................................................1 2 How to Use this Addendum......................................................................................................3 2.1 SWMMWW Volume I......................................................................................................3 2.2 SWMMWW Volume 11.....................................................................................................4 2.3 SWMMWW Volume III....................................................................................................4 2.4 SWMMWW Volume IV...................................................................................................4 2.5 SWMMWW Volume V.....................................................................................................5 2.6 Addendum Content Not Covered in the SWMMWW......................................................5 3 Applicability of the Minimum Requirements...........................................................................7 3.1 Thresholds and Applicability............................................................................................9 3.1.1 Additional Requirements for Road -Related Projects.........................................9 3.1.2 New Connections to the City's MS4..................................................................9 3.1.3 Comparisons to the SWMMWW.....................................................................10 4 Project Basin Location and Applicable Requirements...........................................................11 4.1 Determining Downstream Receiving System(s).............................................................11 4.2 Other Considerations....................................................................................................... I I 5 Project Minimum Requirements.............................................................................................13 5.1 Minimum Requirement No. 1 — Preparation of Stormwater Site Plans ..........................13 5.2 Minimum Requirement No. 2 — Construction Stormwater Pollution Prevention Plan 13 5.3 Minimum Requirement No. 3 — Source Control of Pollution.........................................13 5.4 Minimum Requirement No. 4 — Preservation of Natural Drainage Systems and Outfalls............................................................................................................................14 5.5 Minimum Requirement No. 5 — On -Site Stormwater Management................................15 5.6 Minimum Requirement No. 6 — Runoff Treatment.........................................................17 5.6.1 Edmonds -Specific Oil and Floatables Control.................................................18 5.7 Minimum Requirement No. 7 — Flow Control................................................................18 5.8 Minimum Requirement No. 8 — Wetland Protection.......................................................18 5.9 Minimum Requirement No. 9 — Operation and Maintenance.........................................19 6 Additional Requirements........................................................................................................21 6.1 Protection of LID Facilities During Construction...........................................................21 6.1.1 General Erosion and Sediment Control BMPs Applicable to LID...................21 6.1.2 Additional Construction Techniques for LID BMPs........................................22 edmondsstormwateraddendum 2022 redlines TABLE OF CONTENTS 1 Packet Pg. 88 EDMONDS STORMWATER ADDENDUM 2.4.c OCTOBER 2021 6.1.3 BMP-Specific Construction Techniques..........................................................25 6.2 Off -Site Analyses and Documentation............................................................................28 6.2.1 Category 1 Projects...........................................................................................28 6.2.2 Category 2 Projects...........................................................................................28 6.3 Design Requirements for Detention Vaults and Pipes....................................................30 6.3.1 Sizing & Design................................................................................................31 6.4 Underground Injection Controls......................................................................................31 7 Submittal Requirements..........................................................................................................33 7.1 Category 1 Stormwater Site Plans...................................................................................33 7.2 Category 2 Stormwater Site Plans...................................................................................33 APPENDICES Appendix A — On -Site Stormwater Management BMP Infeasibility Criteria Appendix B — Methods for Determining Design Infiltration Rates Appendix C — Checklists for Various Project Submittal, Review, and Field Procedure Elements Appendix D — Design Checklists for the Main On -Site Stormwater Management BMPs LIST OF FIGURES Figure 3.1. Flow Chart for Determining Requirements for Development.................................8 Figure 7.1. Typical Category 1 Stormwater Site Plan Components........................................33 Figure 7.2. Typical Category 2 Stormwater Site Plan Components........................................34 H TABLE OF CONTENTS zr edmondsstormwoteraddendum 2022 redlines Packet Pg. 89 2.4.c 1 INTRODUCTION This Edmonds Stormwater Addendum (Addendum) provides direction for implementing the City of Edmonds Community Development Code (ECDC) Chapter 18.30, Stormwater Management. The City of Edmonds is required to regulate stormwater discharges to the municipal stormwater system and to waters of the state, in compliance with the Western Washington Phase II National Pollutant Discharge Elimination System (NPDES) Municipal Stormwater Permit (the Permit). Under the Permit, the City must establish and apply the minimum requirements specified in the Permit and provide design guidance for stormwater quality and quantity control for development projects in Edmonds. Through ECDC Chapter 18.30 and this Addendum, the City is complying with federal requirements under the Clean Water Act and the Permit. This Addendum is organized into 7 chapters, briefly summarized below: • Chapter 2 — How to Use this Addendum includes information on how to use the Addendum in conjunction with the ECDC and Ecology's 2019 Stormwater Management Manual for Western Washington (SWMMWW), and to clarify for users where the ECDC, SWMMWW, or Addendum apply. • Chapter 3 — Applicability of the Minimum Requirements includes details on the thresholds that determine the applicability of the minimum requirements to different projects. This information is based on SWMMWW Volume I, Section 3.3, but has been updated to reflect the specific requirements of ECDC 18.30. Chapter 3 also includes a brief summary of how ECDC 18.30.060 compares to the SWMMWW (regarding applicability of the minimum requirements). • Chapter 4 —Project Basin Locations and Applicable Requirements describes downstream receiving waterbodies and/or drainage systems in the city, which will affect how the minimum requirements apply to a given project (primarily Minimum Requirements No. 5, No. 6, and No. 7). Chapter 4 also includes a brief discussion of the unique soil and topographical conditions in the City of Edmonds. • Chapter 5 —Project Minimum Requirements highlights the primary differences between the minimum requirements presented in the SWMMWW and those in the ECDC and provides additional details and guidance to help projects comply with each minimum requirement. • Chapter 6 — Additional Requirements includes additional information on City -specific requirements that are not fully described in the SWMMWW or ECDC. Specific topics include: 1. Additional requirements pertaining to Construction Stormwater Pollution Prevention Plans (SWPPPs) Element No. 13 — Protect Low Impact Development (LID) Best Management Practices (BMPs) 2. Details on the off -site analyses and documentation required to comply with Minimum Requirement No. 4, Preservation of Natural Drainage Systems and Outfalls 1. INTRODUCTION 1 Packet Pg. 90 2.4.c 3. Design requirements for detention vaults and pipes when used to meet Minimum Requirement No. 5 4. Information on Underground Injection Controls (UICs) • Chapter 7 — Submittal Requirements summarizes the process and requirements for preparing project submittals that meet the requirements of the SWMMWW, the ECDC, and this Addendum The appendices included in this Addendum provide additional background information and requirements related to stormwater management in the city. (Also note that there are several additional pertinent appendices within the SWMMWW that are adopted by reference.) The following City -specific appendices are included in this Addendum: • Appendix A — On -Site Stormwater Management BMP Infeasibility Criteria • Appendix B — Methods for Determining BMP Design Infiltration Rates • Appendix C — Checklists for Various Project Submittal, Review, and Field Procedure Elements o Checklist 1 — Category 1 Stormwater Site Plans o Checklist 2 — Category 2 Stormwater Site Plans o Checklist 3 — Construction SWPPP Drawings and Report o Checklist 4 — Methods for Determining Infiltration Rates o Checklist 5 — Field and Design Procedures for Bioretention, Permeable Pavement, Rain Gardens, and Downspout Infiltration Systems o Checklist 6 — Procedures for Infiltration Trenches and Basins • Appendix D — Design Checklists for the Main On -Site Stormwater Management BMPs o Checklist 7 — Post -Construction Soil Quality and Depth o Checklist 8 — Sheet Flow Dispersion o Checklist 9 — Concentrated Flow Dispersion o Checklist 10 — Bioretention Cells, Swales, and Planter Boxes o Checklist 11 — Permeable Paving o Checklist 12 — Rain Gardens o Checklist 13 — Downspout Infiltration o Checklist 14 — Downspout Dispersion o Checklist 15 — Perforated Stub -out Connections 2 1. INTRODUCTION Packet Pg. 91 2.4.c 2 HOW TO USE THIS ADDENDUM Review ECDC Chapter 18.30.030 and 18.30.040 to determine if the City's Stormwater Code and this Addendum apply to your project. Review the definitions section of ECDC Chapter 18.30.10 (and if necessary the Glossary in SWMMWW Volume I, Appendix G for clarification on terminology used in ECDC Chapter 18.30 and this Addendum. As per ECDC Chapter 18.30.60, the stormwater management requirements in the City of Edmonds — including but not limited to thresholds, definitions, minimum requirements, adjustment and variance criteria, and exceptions to these requirements — shall be governed by the 2019 SWMMWW, with additional requirements and modifications as outlined in the provisions of ECDC Chapter 18.30 and this Addendum. Project proponents must review ECDC 18.30 (18.30.060 in particular) and this Addendum to identify how the City's requirements and the requirements of the SWMMWW apply to a given project. In the event of inconsistencies between the various provisions, the more stringent provisions shall apply, unless otherwise approved by the City. Where requirements in this Addendum are also covered in any other law, ordinance, resolution, rule, or regulation of any kind (i.e., outside of ECDC Chapter 18.30), the more restrictive requirement shall govern, unless otherwise approved by the City. This Addendum includes information to supplement or elaborate on the guidelines and requirements outlined in ECDC Chapter 18.30 and the SWMMWW. To highlight for Addendum users where the ECDC, SWMMWW, or Addendum apply, the following sections outline the general applicability of each document, summarized according to the organization of the SWMMWW. Note however that the SWMMWW is not always written in a manner that is suitable as a municipal regulatory tool, therefore there are known overlaps among the ECDC, SWMMWW, and Addendum. As such, this section is only intended to be a guide, not a definitive resource on SWMMWW applicability. When questions or potential inconsistencies arise, project proponents should contact the City for clarification and interpretation. 2.1 SWMMWW VOLUME I • Chapter 1 — Introduction: Adopted in its entirety. • Chapter 2 — Relationship of This Manual to Permits, Requirements, and Programs: Adopted in its entirety. • Chapter 3 — Minimum Requirements for New Development and Redevelopment: Users should refer first to ECDC Chapter 18.30.60 and this Addendum. Note that some portions of ECDC 18.30.60 refer back to the SWMMWW as well as specific sections of this Addendum. o In addition, for all minimum requirements that require flow modeling, unless otherwise specified, all continuous modeling shall be performed using the "Puget East 36" precipitation time series, consisting of a 158-year precipitation and evaporation time series that are representative of the climatic conditions in the City of Edmonds. This time series is available in WWHM (select "Use WS-DOT data") and MGSFlood (Extended Timeseries menu). 2. HOW TO USE THIS ADDENDUM 3 Packet Pg. 92 2.4.c o In addition, ECDC 18.30 includes an additional "retro-fit" specific to Minimum Requirement #5; see ECDC 18.30.060.D.5.b.i. • Chapter 4 — UIC Program: Adopted in its entirety. All UICs within Edmonds shall comply with the applicable requirements of this section. • Appendices —Use Appendix G for the SWMMWW only and refer to ECDC Chapter 18.30.10 for ECDC definitions. 2.2 SWMMWW VOLUME II • SWMMWW Volume II is adopted in its entirety. o In addition, this Addendum includes supplemental information to support compliance with SWMMWW Minimum Requirement No. 2, Element No. 13 — Protect Low Impact Development BMPs. See Chapter 6. 2.3 SWMMWW VOLUME III • Chapter 1 — Choosing you BMPs: Chapter adopted in its entirety. o The infeasibility criteria typically are included within the specific BMP descriptions in the SWMMWW, but are summarized in Appendix A for clarity and ease of use. Appendix A also includes additional BMP infeasibility criteria that are specific to the City of Edmonds, and not necessarily included in the 2014 SWMMWW. o In addition, ECDC 18.30 adds detention to the list of BMPs to be considered under minimum requirement #5; see ECDC 18.30.060.D.5. • Chapter 2 — Modelling Your BMPs: Chapter adopted in its entirety. o In addition, Checklist 8 thru 15 of this Addendum include checklists for designing BMPs. • Chapter 3 — Preparation of Stormwater Site Plans: Refer first to Chapter 7 of this Addendum, and associated Appendix C, Checklists 1 through 3. The requirements of SWMMWW Volume III, Chapter 3 apply to projects in Edmonds, but Chapter 7 of this Addendum has been created to facilitate compliance with both the SWMMWW requirements for preparation of Stormwater Site Plans, as well as additional City -specific submittal requirements. 2.4 SWMMWW VOLUME IV • SWMMWW Volume IV is adopted in its entirety. 4 2. HOW TO USE THIS ADDENDUM Packet Pg. 93 2.4.c 2.5 SWMMWW VOLUME V • SWMMWW Volume V is adopted in its entirety. o In addition, this Addendum includes supplemental information to support determination of On -Site Stormwater Management BMP infeasibility. Specifically, Appendix A of this Addendum summarizes infeasibility criteria that apply to each BMP (to be used in complying with Minimum Requirement No. 5). The infeasibility criteria typically are included within the specific BMP descriptions in the SWMMWW, but are summarized in Appendix A for clarity and ease of use. Appendix A also includes additional BMP infeasibility criteria that are specific to the City of Edmonds, and not necessarily included in the 2019 SWMMWW. Where there are differences between the SWMMWW and Appendix A, the requirements in Appendix A shall apply unless otherwise approved by the City. o In addition, this Addendum include design requirements for detention tanks and vaults to meet the Edmonds -specific application of a detention as a BMP for Minimum Requirement #5 in Section 6.3. o In addition, ECDC 18.30 includes a "retrofit" provision under Minimum Requirement #5 which requires mitigating a portion of existing unmitigated hard surfaces to remain on a project site; see ECDC 18.30.060.D.5.b.i 2.6 ADDENDUM CONTENT NOT COVERED IN THE SWMMWW T Note that in addition to the items included in Sections 2.1 through 2.5 above, this Addendum includes extensive information that is unique to the City and not tied to a specific SWMMWW volume or issue. Therefore, in addition to the notes above, users must review all of this Addendum and ECDC 18.30 for applicable requirements. This includes the Appendices and checklists included in this Addendum (particularly the BMP design checklists), which contain City -specific design, procedural, and submittal requirements that may not be reflected in the SWMMWW or ECDC. • In addition, as noted in Section 2.1 above, unless otherwise specified, all continuous modeling shall be performed using the "Puget East 36" precipitation time series, consisting of a 158-year precipitation and evaporation time series that are representative of the climatic conditions in the City of Edmonds. This time series is available in WWHM (select "Use WS-DOT data") and MGSFlood (Extended Timeseries menu). • The use of corrugated metal pipe within Edmonds is prohibit on both private and public properties storm drain conveyance and /or BMPs (i.e. detention tanks). 2. HOW TO USE THIS ADDENDUM 5 Packet Pg. 94 2.4.c 0 CM Oo r U a V W d O U r c 0 E 0 tm cv c L d 3 E L O 4- 0 r_ O N L a c a� U I E 7 C d Q L d 3 E L O Cl) N C O E W N N N I U r c a) E t v cv r r Q c O E t u 2 Q Packet Pg. 95 2.4.c 3 APPLICABILITY OF THE MINIMUM REQUIREMENTS This chapter is based on SWMMWW Volume I, Section 2.4, however the content below has been updated to reflect the specific requirements of ECDC 18.30. Project proponents must review ECDC 18.30 in detail. The following provides additional information and direction on the thresholds and applicability of minimum requirements outlined in ECDC 18.30.060. Project proponents must be aware that not all of the minimum requirements apply to every development project. The applicability varies depending on the project type and size. This chapter summarizes thresholds that determine the applicability of the minimum requirements to different projects. Review ECDC 18.30.060 and use the flow chart in Figure 3.1 to determine which of the minimum requirements apply to your project. (The minimum requirements themselves are provided in 18.30.060.D and are summarized in Chapter 5 of this Addendum). The thresholds described below and in Figure 3.1 are to be determined at the time of application for a subdivision, plat, short plat, building permit, or other construction permit. For projects involving only land disturbing activities, (e.g., clearing or grading), the thresholds apply at the time of application for the permit allowing or authorizing that activity. 3. APPLICABILITY OF THE MINIMUM REQUIREMENTS 7 Packet Pg. 96 2.4.c Does the project result in 2,000 square feet, or greater, of new plus replaced hard surface area? OR Does the land disturbing activity total 7,000 square feet or greater? Yes No Minimum Requirements No. 1 through 5 apply I Minimum Requirement No. 2 applies Next Question IF Does the project add 5,000 square feet or more of new plus replaced hard surfaces? OR Convert 0.75 acres or more of vegetation to lawn or landscaped areas? OR Convert 2.5 acres or more of native vegetation to pasture? No Yes No Is this a road related project? All Minimum Requirements apply to the new and replaced Yes hard surfaces and converted vegetation areas. All Minimum Requirements apply to the new hard surfaces and converted vegetation areas. Yes Does the project add 5,000 square feet or No more of new hard surfaces? Yes Do new hard surfaces add 50% or more to the existing hard surfaces within the project limits? No Figure 3.1. Flow Chart for Determining Requirements for Development. No additional requirements. 8 3. APPLICABILITY OF THE MINIMUM REQUIREMENTS Packet Pg. 97 2.4.c 3.1 THRESHOLDS AND APPLICABILITY All development shall be required to comply with Minimum Requirement No. 2. The following Category 1 project sites shall comply with Minimum Requirements No. 1 through No. 5: • Results in 2,000 square feet, or greater, of new plus replaced hard surface area, or • Have land disturbing activity of 7,000 square feet or greater. The following Category 2 project sites shall comply with Minimum Requirements No. 1 through No. 9: • Results in 5,000 square feet or more of new plus replaced hard surfaces, or • Converts 0.75 acres, or more, of vegetation to lawn or landscaped areas, or • Converts 2.5 acres, or more, of native vegetation to pasture. 3.1.1 Additional Requirements for Road -Related Projects For road -related projects, runoff from the new hard surfaces (including pavement, shoulders, curbs, and sidewalks) and the converted vegetation areas shall meet all the minimum requirements if the new hard surfaces total 5,000 square feet or more. In addition, if the new hard surfaces total 5,000 square feet or more and total 50 percent or more of the existing hard surfaces within the project limits, runoff from the new and replaced hard surfaces and the converted vegetation areas shall meet all the minimum requirements. The project limits shall be defined by the length of the project and the width of the right-of- way. 3.1.2 New Connections to the City's MS4 When a property owner proposes a new connection to the City's Municipal Separate Storm Sewer System (MS4), and the situation either 1) does not exceed the Category 1 or Category 2 thresholds above, or 2) does not involve activity that meets the definition of development, the following applies: • Sites that are not currently connected to the City's MS4 but wish to connect directly or indirectly to the City's MS4 may be allowed on a case -by -case basis, subject to City approval. • For sites that propose to drain greater than or equal to 2,000 square feet of hard surface area to the City's MS4, the project shall comply with the requirements of this chapter, treating all hard surfaces to be drained to the City system as new hard surfaces, unless applicant can demonstrate that the site will discharge in the same manner and quantities prior to the proposed project. Applicant shall account for natural dispersion and/or infiltration which may be occurring if these new hard surfaces area currently drain through pervious areas in their analysis. 3. APPLICABILITY OF THE MINIMUM REQUIREMENTS 9 Packet Pg. 98 2.4.c 3.1.3 Comparisons to the SWMMWW Project proponents must review ECDC 18.30 in detail, but the following notes are provided to help clarify how ECDC 18.30.060 compares to the SWMMWW regarding applicability of the minimum requirements (see Chapter 5 for additional details on the individual minimum requirements and how they differ from the SWMMWW): 1. ECDC 18.30 refers to "Category 1" projects and "Category 2" projects. See ECDC 18.30.060 for complete details, but in general: O Category 1 project sites result in 2,000 square feet, or greater, of new plus replaced hard surface area and shall comply with Minimum Requirements No. 1 through No. 5. O Category 2 project sites result in 5,000 square feet, or greater, of new plus replaced hard surface area and shall comply with Minimum Requirements No. 1 through No. 9. 2. ECDC 18.30 does not differentiate between new development and redevelopment. 3. Information regarding which surfaces each minimum requirement applies to (e.g., new hard surfaces, replaced hard surfaces, or both) is typically discussed under each minimum requirement as opposed to within the initial applicability section. 4. In addition to item No. 3 above, ECDC 18.30.060.D.5.b includes a retrofit requirement for projects that discharge directly or indirectly to the City's MS4 and that contain existing hard surfaces that do not drain to an approved stormwater management facility. These projects are required to provide On -site Stormwater Management BMPs to manage a portion (a minimum of 25 percent) of those existing hard surfaces that will remain after project completion. See ECDC 18.30.060.D.5.b for complete details on this requirement. 5. ECDC 18.30.060.D.5 also adds detention as a BMP to be considered for feasibility under Minimum Requirement #5 in additional to those in SWMMWW, see Section 6.3. 6. As per the SWMMWW, for road -related projects, if the new hard surfaces total 5,000 square feet or more and total 50 percent or more of the existing hard surfaces within the project limits, runoff from the new and replaced hard surfaces shall meet all the minimum requirements. Otherwise, the minimum requirements only apply to the new hard surfaces (if the new hard surfaces total 5,000 square feet or more). Unlike the SWMMWW, non -road -related projects do not have to assess the valuation of the proposed improvements in order to determine the applicability of the minimum requirements. In general, once triggered by the applicable project area thresholds (see below and ECDC 18.30.060), the minimum requirements apply to both new and replaced hard surfaces. 7. ECDC 18.30 and this Addendum also includes requirements for new connections to the City's MS4, when the proposed connection does not involve activity that meets the definition of development. See the previous section of this Addendum for additional information on new connections. 8. ECDC 18.30 and this Addendum modify the flow modelling basin to be used in modelling, see Section 2.6. 9. ECDC 18.30 and this Addendum requires use of the phosphorus treatment menu within the Hall's Creek and Lake Ballinger basins; see Section 5.6. 10. Section 5.3, below, prohibits the use of corrugated metal piping (CMP) within Edmonds. 10 3. APPLICABILITY OF THE MINIMUM REQUIREMENTS Packet Pg. 99 2.4.c 4 PROJECT BASIN LOCATION AND APPLICABLE REQUIREMENTS 4.1 DETERMINING DOWNSTREAM RECEIVING SYSTEM(S) Broadly speaking, stormwater runoff in the City of Edmonds either travels west to Puget Sound (via a creek or piped system) or to the east to Lake Ballinger or Hall Creek, which discharges to Lake Ballinger. In addition to assessing the new and replaced hard surfaces and converted vegetation areas associated with a project, the minimum requirements (primarily Minimum Requirements No. 5, No. 6, and No. 7) can also vary depending on the project's downstream receiving waterbody and/or drainage system. The specific details of each minimum requirement are outlined in Chapter 5, but in general, projects should determine what type of system(s) their project site drains to early in the development process: The two primary systems to be aware of are described below. Note that these systems are not mutually exclusive: 1. Direct Discharge areas: Those site areas that discharge runoff directly to Puget Sound via a constructed conveyance system (e.g., pipe or ditch) without first entering a creek or other receiving water. (See Section 3.4.7 of Volume I of the SWMMWW for the full list of restrictions that must be met to qualify as a direct discharge.) 2. City of Edmonds Municipal Separate Storm Sewer System (MS4): Those site areas that discharge to the City's MS4 before ultimately discharging to a downstream receiving water (e.g., a creek, lake, or Puget Sound). See the City's NPDES Municipal Stormwater Permit for the complete MS4 definition, but this generally includes sites that discharge to a dedicated stormwater conveyance system (including roads with drainage systems, ditches, manmade channels, or storm drains) owned or operated by the City and that discharge to waters of Washington State (including creeks, lakes, ponds, wetlands, and Puget Sound). A map of watersheds in Edmonds is available via the Edmonds GIS Map that can be accessed on the City's website here: (<www.maps.edmondswa.gov>). Direct Discharge Basins are those labeled "Puget Sound" or "Puget Sound Piped." Edmonds Way is known to have an overflow under certain conditions which creates a discharge to Edmonds Marsh (not considered man-made drainage course for the purposes of this exemption), and therefore the Edmonds Way basin shall not be considered a direct discharge basin. An applicant with site -specific information that is contrary to the basin designations shown in Figure B-1 can present this information to the Public Works Director (Director) or designee for a possible change in basin designation. The Director or designee will make a determination on any requests for a site -specific change in basin designation. 4.2 OTHER CONSIDERATIONS Edmonds is fortunate to be located adjacent to Puget Sound and possess topography that facilitates desirable views. The underlying soils and relatively steep slopes, however, complicate the application of stormwater management techniques. 4. PROJECT BASIN TYPE AND APPLICABLE REQUIREMENTS 11 Packet Pg. 100 2.4.c Prior to logging and subsequent development of the Edmonds area, trees and the forest duff layer above the soil surface (consisting primarily of needles, leaves, branches, bark, and stems in various stages of decomposition) covered the city. With logging came the elimination of the majority of the tree canopy and the duff layer, and with it the elimination of the water -holding capacity of the natural land cover. hi the majority of the city, the soils that remain (after forest removal and subsequent development) consist of till or hard pan, which is much less effective at storing or absorbing rainwater. Although this Addendum and the SWMMWW place substantial emphasis on the use of infiltration and on -site stormwater management techniques, the soil regime in the City of Edmonds can make this goal challenging. It is therefore important that project sites thoroughly investigate and understand their soil conditions (as well as other site conditions such as slope, groundwater levels, etc.) before proceeding too far with the site stormwater design. See the submittal checklists in Appendix C (Checklists 1 through 3), BMP infeasibility criteria in Appendix A, and SWMMWW for additional details and requirements. In addition to challenging soil conditions, approximately 25 percent of the land area in the City of Edmonds has a slope of 15 percent or greater or is in an Earth Subsidence and Landslide Hazard Area (the Meadowdale area in the northernmost portion of the city). Geologic hazards in these areas can be increased when stormwater runoff from impervious surfaces percolates into the soil. As emphasized in the submittal checklists in Appendix C (Checklists 1 through 3), BMP infeasibility criteria in Appendix A, and SWMMWW Chapter 3; consideration of slopes in the project vicinity is a critical component of the site stormwater design. 12 4. PROJECT BASIN TYPE AND APPLICABLE REQUIREMENTS Packet Pg. 101 2.4.c 5 PROJECT MINIMUM REQUIREMENTS This chapter should be used as a supplement to ECDC 18.30.060.D and SWMMWW Volume I, Chapter 3 as it emphasizes the key differences between the minimum requirements outlined in the SWMMWW and those outlined in ECDC 18.30.060.D. Project proponents must still review ECDC 18.30.060.D in detail, but the following text provides additional information and direction on the minimum requirements outlined in ECDC 18.30.060.D. As noted previously in Chapter 4, once a given minimum requirement is triggered (per the thresholds in Chapter 3), the specifics of the minimum requirement may vary depending on the project downstream receiving waterbody and/or drainage system. 5.1 MINIMUM REQUIREMENT NO. 1 - PREPARATION OF STORMWATER SITE PLANS Stormwater Site Plans are required for all projects subject to Minimum Requirement No. 1, as outlined in Chapter 3 and ECDC 18.30.060.C. Stormwater Site Plans shall be prepared in accordance with Chapter 3 of Volume III of the SWMMWW. However, because Chapter 3 of the SWMMWW includes extensive technical requirements, but does not explicitly specify how those requirements shall be consistently documented, submitted, and/or reviewed for a typical development project, the City of Edmonds has developed project checklists to facilitate compliance with this minimum requirement (and thus project submittal and review). Those checklists are introduced in Chapter 7 and provided in Appendix C, Checklists 1 through 3. 5.2 MINIMUM REQUIREMENT NO. 2 - CONSTRUCTION STORMWATER POLLUTION PREVENTION PLAN See ECDC 18.30.060.D.2. In addition, note that ECDC 18.30.060.D.2.d.i points to the SWMMWW Chapter 3, Section 3.4.2 for details on the requirements for Construction Stormwater Pollution Prevention Plans (SWPPPs), including the 13 Elements that must be reflected in the Construction SWPPP. See Chapter 6 for additional requirements pertaining to Construction SWPPP Element No. 13 — Protect Low Impact Development BMPs, which are not provided in the SWMMWW. 5.3 MINIMUM REQUIREMENT NO. 3 - SOURCE CONTROL OF POLLUTION See ECDC 18.30.060.D.3 and SWMMWW Volume IV. Note that all single-family residential projects shall, at a minimum, incorporate required BMPs from SWMMWW Volume IV, S411 — BMPs for Landscaping and Lawn/Vegetation Management. 5. PROJECT MINIMUM REQUIREMENTS 13 Packet Pg. 102 2.4.c Corrugated metal pipe (CMP) has been found to be a routine failure problem in Edmonds and a potential source of additional sediment in the City system. For this reason, CMP pipe is not permitted within Edmonds on either pulic or private property or both conveyance storm pipe and for detention tanks. 5.4 MINIMUM REQUIREMENT NO. 4 - PRESERVATION OF NATURAL DRAINAGE SYSTEMS AND OUTFALLS See ECDC 18.30.060.D.4 and the content presented below. Although this minimum requirement is based on Minimum Requirement No. 4 in SWMMWW Volume I, Section 3.4.4, there are enough differences between the City's requirements and those in the SWMMWW that project proponents should not refer to the SWMMWW for Minimum Requirement No. 4. Only ECDC 18.30.060.D.3 and the following shall be required. To demonstrate compliance with this minimum requirement, all projects shall submit as part of their Stormwater Site Plan an off -site analysis that assesses the potential off -site impacts of stormwater discharges. (See the end of this section, and Chapter 6, for details on the requirements for analysis and documentation.) Natural drainage patterns shall be maintained, and discharges from the project site shall occur at the natural location, to the maximum extent practicable. The manner by which runoff is discharged from the project site must not cause a significant adverse impact to downstream receiving waters or down gradient properties. The discharge must have an identified overflow route that is safe and certain, and leads to the ultimate outfall location (such as a receiving water or municipal drainage system). All outfalls require energy dissipation. (Designs for outfall systems to protect against adverse impacts from concentrated runoff are included in SWMMWW Volume V, Chapter 1.) In addition, existing upstream flows must be accommodated without causing erosion or flooding impacts. Upstream drainage means drainage from adjacent property that enters the proposed project site (other than a defined natural channel). Upstream flows shall not be routed through the project's conveyance, treatment, or retention/detention systems, unless those systems are sized to control those flows. Upstream flows that are collected and routed through or around the site in a separate conveyance shall be dispersed at the downgradient property line, if feasible, or discharged at a project outfall (or outfalls) in a manner that does not violate the criteria below or cause the capacity of a conveyance system to be exceeded. Where no conveyance system exists at the adjacent downgradient property line and the discharge was previously unconcentrated flow or significantly lower concentrated flow, measures must be taken to prevent downgradient impacts. Drainage easements from downstream property owners may be needed and should be obtained prior to approval of engineering plans. For Category 2 projects only — where no conveyance system exists at the adjacent downstream property line and the natural (existing) discharge is unconcentrated, any runoff concentrated by the proposed project, including upstream drainage, must be discharged as follows: 1. If the 100-year peak discharge is less than or equal to 0.2 cfs (0.3 cfs using 15-minute time steps) under existing conditions and will remain less than or equal to 0.2 cfs under developed conditions, then the concentrated runoff may be discharged onto a rock pad or to any other system that serves to disperse flows. 2. If the 100-year peak discharge is between 0.2 and 0.5 cfs (or 0.75 cfs using 15-minute time steps) under existing conditions and will remain in that range under developed conditions, then the 14 5. PROJECT MINIMUM REQUIREMENTS Packet Pg. 103 2.4.c concentrated runoff may be discharged through a dispersal trench or other dispersal system, provided the applicant can demonstrate that there will be no significant adverse impact to downhill properties or drainage systems. 3. If the 100-year peak discharge is greater than 0.5 cfs for either existing or developed conditions, or if a significant adverse impact to downgradient properties or drainage systems is likely, then a conveyance system shall be provided to convey the concentrated runoff across the downstream properties to an acceptable discharge point (i.e., an enclosed drainage system or open drainage feature where concentrated runoff can be discharged without significant adverse impact). To demonstrate compliance with this minimum requirement, all projects shall submit as part of their Stormwater Site Plan an off -site analysis that assesses the potential off -site impacts of stormwater discharges. Off -site analyses shall assess upstream and downstream conditions, including the conveyance capacity and erosion potential in the downstream system. If a problem is found, mitigation is required to prevent worsening of that problem or to mitigate an existing flooding or erosion problem. The off -site analysis shall include, at a minimum, a qualitative analysis of each upstream drainage system entering a site, and each downstream drainage system leaving a site. A quantitative analysis may be required for any project deemed to need additional downstream information or where the project proponent or the City determines that a quantitative analysis is necessary to evaluate the off -site impacts or the capacity of the conveyance system (e.g., where there is evidence of a risk to downstream systems such as erosion, flooding, property damage, habitat damage, water quality degradation, or other related impacts). See Chapter 6 for additional details on off -site analyses and documentation. 5.5 MINIMUM REQUIREMENT NO. 5 - ON -SITE STORMWATER MANAGEMENT The City has made several additions and changes to the contents of Minimum Requirement No. 5 relative to the SWMMWW. Project proponents must review ECDC 18.30.060.D.5 in detail to ensure all City - specific requirements are addressed. This section of the Addendum provides a summary of the City - specific elements of Minimum Requirement No. 5. In addition, this Addendum includes several tools to support implementation of Minimum Requirement No. 5 and related requirements. These tools include: A summary of infeasibility criteria for all On -Site Stormwater Management BMPs (see Appendix A). These infeasibility criteria must be considered when evaluating the feasibility of On -Site Stormwater Management BMPs as part of List No. 1 or List No. 2. The infeasibility criteria are included within the specific BMP descriptions in the SWMMWW, but are summarized in Appendix A for clarity. Appendix A also includes additional BMP infeasibility criteria that are specific to the City of Edmonds, and not necessarily included in the 2019 SWMMWW. 2. A summary of acceptable methods for determining BMP design infiltration rates (see Appendix B; and Appendix C, Checklist 4). Initial site infiltration rates may be determined either using field testing procedures, or the Soil Grain Size Analysis Method. These methods are described in detail in Appendix B. 5. PROJECT MINIMUM REQUIREMENTS 15 Packet Pg. 104 2.4.c A summary of site investigation and field and design procedures required for several of the On - Site Stormwater Management BMPs as well as for infiltration basins and trenches (see Appendix C, Checklists 5 and 6). The field and design procedures required to design and implement On -Site Stormwater Management BMPs can be considerable, and include issues such as determining infiltration rates, determining depth to groundwater or other impermeable layers, soils reporting requirements, etc. 4. Submittal checklists for Category 1 and Category 2 projects, including notes on project site, soil, and BMP design information that must be documented and submitted to the City to meet the City of Edmonds and SWMMWW requirements related to Minimum Requirement No. 5 (and other minimum requirements. See Appendix C, Checklists 1 through 3. 5. Design checklists for most of the On -Site Stormwater Management BMPs in List No. 1 and List No. 2 (see Appendix D). The applicability of Minimum Requirement No. 5 depends on the project type, project location, and the existing and proposed surfaces at the project site. See ECDC 18.30.060.D.5 for details, but in summary: Projects that drain directly or indirectly to the City's MS4 and that contain existing hard surfaces that do not drain to an approved stormwater management facility are required to provide On -Site Stormwater Management BMPs to manage a minimum of 25 percent of those existing hard surfaces that will remain after the project. The intent is to bring a portion of any existing, unmanaged surfaces up to current standards. If the 25 percent minimum is met, projects are not required to evaluate BMPs in priority order or document infeasibility for these existing surfaces (as per the subsequent project scenarios). 2. Similar to the SWMMWW, Category 1 project sites (project sites subject to Minimum Requirements No. 1 through No. 5) that discharge directly or indirectly to the City's MS4 shall either use On -Site Stormwater Management BMPs from List No. 1 (see ECDC 18.30.060.D.5.d) for all new plus replaced hard surfaces and land disturbed, or demonstrate compliance with the LID Performance Standard (See ECDC 18.30.060.D.5.c). Note that in the City of Edmonds, List No. 1 includes detention vaults or pipes as the final BMP option for roofs and other hard surfaces. See Chapter 6 for associated design requirements for detention vaults and pipes, including simplified sizing methods for meeting Minimum Requirement No. 5. (Note also that if the project is required to construct a flow control facility to comply with Minimum Requirement No. 7 (per ECDC 18.30.060.D.7), a detention vault or pipe is not required to be installed to meet Minimum Requirement No. 5.) Categor,2project sites (project sites subject to Minimum Requirements No. 1 through No. 9) are subject to similar requirements as Category 1 projects, but must use List No. 2 instead of List No. 1 (see ECDC 18.30.060.D.5.e). 4. Projects that discharge directly to Puget Sound through the City's MS4 (in accordance with the restrictions applicable to direct discharges to Puget Sound presented in Section 2.5.7 of Volume I of the SWMMWW) do not have to achieve the LID Performance Standard, and only have to evaluate a subset of the BMPs in List No. 1 or List No. 2. 5. Projects that do not drain directly or indirectly to the City's MS4 are required to either: o Discharge to the downstream private property (with approval) 16 5. PROJECT MINIMUM REQUIREMENTS Packet Pg. 105 2.4.c o Discharge runoff to an on -site system from List No. 1 (see in ECDC 18.30.060.D.5.d). ■ Sites located within earth subsidence and landslide hazard areas or their buffers are not required to evaluate BMPs in priority order or document infeasibility. However, a geotechnical design, analysis, and report by a geotechnical engineer is required. ■ For sites located outside earth subsidence and landslide hazard areas or their buffers, projects must meet applicable Category 1 or Category 2 project requirements for Minimum Requirement No. 5 (see ECDC 18.30.060.D.5.ii and ECDC 18.30.060.D.5.iii). o Project sites may pump on -site runoff to the City's MS4, with prior approval; in such cases, projects shall meet all provisions of ECDC 18.30 as they would drain to the MS4 in post project conditions. 6. Finally, the following guidance shall be used to help clarify the requirements in the SWMMWW specific to List No. 1 and No. 2. Where the SWMMWW and ECDC 18.30.060.D.5.d/e states that "for each surface, consider the BMPs in the order listed for that type of surface. Use the first BMP that is considered feasible. No other On -Site Stormwater Management BMP is necessary for that surface" the following clarifications are provided: o The goal of List No. 1 and List No. 2 is to manage 100 percent of each surface. If a project cannot manage 100 percent of a given surface with the first feasible BMP, a second BMP may be required to manage the remaining unmanaged area (depending on the size of the unmanaged area and the site -specific constraints). For example, where a roof surface drains to multiple downspouts around the perimeter of the structure, it is generally insufficient to only manage runoff that drains to a single downspout and to leave the remaining downspouts unmanaged (i.e., due to infeasibility considerations). 7. For BMPs without specific sizing criteria in this Addendum, single family residential projects under 2,000 SF of new plus replaced hard surfaces only, may use the simplified sizing per the included checklist for each BMP or per Volume V of SWMMWW to satisfy Minimum Requirement #5. However, such sizing methodology shall be assumed to generate an overflow and a piped or subsurface overflow connection is required for such BMPs unless otherwise waived by the City. 5.6 MINIMUM REQUIREMENT NO. 6 - RUNOFF TREATMENT See ECDC 18.30.060.D.6 for thresholds and core requirements. See the SWMMWW for additional information on complying with this minimum requirement. In particular, the following sections should be reviewed: • Volume I, Section 3.4.6 for details on treatment facility sizing • Volume I, Chapter 4 and Volume V, Chapters 2 and 3 for general BMP selection. Note also that phosphorus treatment is required for projects that drain to Hall Creek or Lake Ballinger. • Volume V for design and maintenance requirements. 5. PROJECT MINIMUM REQUIREMENTS 17 Packet Pg. 106 2.4.c 5.6.1 Edmonds -Specific Oil and Floatables Control In addition to the oil control requirements in the SWMMWW, all projects in the City of Edmonds not zoned as single-family residential that collect runoff from five or more parking spaces shall install floatable controls in catch basins (if another approved floatable control system is not employed). 5.7 MINIMUM REQUIREMENT NO. 7 — FLOW CONTROL See ECDC 18.30.060.D.7 for thresholds and core requirements. See the SWMMWW for additional information on complying with this minimum requirement (in particular, Volume I, Section 3.4.7). Note that flow control in accordance with Minimum Requirement No. 7 is not required for projects that discharge directly to, or indirectly through the City's MS4 to Puget Sound (other minimum requirements still apply, including Minimum Requirement No. 6, as well as Minimum Requirement No. 5 and the Edmonds Way direct discharge requirements). See ECDC 18.30.060.D.5.b.iv and Section 3.4.7 of Volume I of the SWMMWW for additional restrictions applicable to direct discharges to Puget Sound. In addition, the following information may be useful in determining the applicability of Minimum Requirement No. 7, specifically per the 100-year flow frequency threshold outlined in ECDC 18.30.060.D.7.b.iii: Calculations to determine whether a project exceeds the 0.10 cubic feet per second (cfs), using a 1-hour time step (or 0.15 cfs using a 15-minute time step) increase in the 100-year recurrence interval flow must be performed individually for each project using an approved continuous simulation runoff model. The calculation will compare runoff in the post development site to the pre -development land cover. Pre - development, for this activity only, is the lower runoff of the pre project condition, or the site on July 6, 1977 (the effective date of the City's first drainage control ordinance). The unique site, soil, precipitation, and other project -specific factors will ultimately determine whether this threshold is exceeded. Nonetheless, the following general guidelines (based on hypothetical site designs) may be used to help identify the likelihood of this threshold being exceeded. The following land use changes are likely to exceed this threshold under certain conditions: • Converting approximately 5,000 square feet of forest to hard surface • Converting approximately 5,000 square feet of pasture to hard surface • Converting approximately 0.25 acres of forest to landscape surface • Converting approximately 1.25 acres of forest to pasture surfaces (in till soil conditions) 5.8 MINIMUM REQUIREMENT NO. H — WETLAND PROTECTION See ECDC 18.30.060.D.8 and SWMMWW Volume I, Section 3.4.8. See also SWMMWW Volume I, Appendix I-C. 18 5. PROJECT MINIMUM REQUIREMENTS Packet Pg. 107 2.4.c 5.9 MINIMUM REQUIREMENT NO. 9 - OPERATION AND MAINTENANCE See ECDC 18.30.060.D.9. See also the submittal checklists provided in Appendix C, Checklists 1 through 3 (also referenced previously as part of Minimum Requirements No. 1 and No. 5) for notes about submittal requirements related to the required operation and maintenance manual. 5. PROJECT MINIMUM REQUIREMENTS 19 Packet Pg. 108 2.4.c 0 CM Oo r U a V W d O U r c 0 E 0 tm cv c L d 3 E L O 4- 0 r_ O N L a c a� U I E 7 C d Q L d 3 E L O Cl) N C O E W N N N I U r c a) E t v cv r r Q c O E t u 2 Q Packet Pg. 109 2.4.c 6 ADDITIONAL REQUIREMENTS This chapter includes additional requirements that are either not included in the SWMMWW, or that are supplemental to the information provided in the SWMMWW. Specifically, this chapter addresses: 1. Additional requirements pertaining to Construction SWPPP Element No. 13 — Protect Low Impact Development BMPs (required in the SWMMWW. 2. Details on the off -site analyses and documentation required to comply with Minimum Requirement No. 4, Preservation of Natural Drainage Systems and Outfalls (City of Edmonds specific). 3. Design requirements for detention vaults and pipes when used to meet Minimum Requirement No. 5. 4. Information on Underground Injection Controls (UICs). 6.1 PROTECTION OF LID FACILITIES DURING CONSTRUCTION To ensure that LID stormwater facilities and BMPs will be fully functional after construction, it is important to protect these BMPs during construction activities. Protecting native soil and vegetation, minimizing soil compaction, and retaining the hydrologic function of LID BMPs during the site preparation and construction phases are some of the most important practices during the development process. The purpose of this section is to provide designers, builders, and inspectors with guidance and tools for meeting Minimum Requirement No. 2, Element No. 13 — Protect Low Impact Development BMPs. This section does not provide guidance on construction or design of LID BMPs (see SWMMWW Volume III and Volume V), or cover all Construction SWPPP practices (see SWMMWW Volume II), but rather focuses on how to most efficiently reduce impacts on LID BMPs specifically during construction. The practices specified in this section must be applied to protect LID BMPs, unless the given practice does not apply to the project site conditions or activities. 6.1.1 General Erosion and Sediment Control BMPs Applicable to LID Overall Construction Stormwater Pollution Prevention Plan (SWPPP) requirements are specified in Chapter 5, Minimum Requirement No. 2 and SWMMWW Volume II. In general, Construction SWPPP BMPs limit the impact of site disturbance, erosion, and sediment deposition during construction. Some Construction SWPPP BMPs focus on providing a physical barrier or deterrent to help minimize construction -related site disturbance and/or erosion, while other Construction SWPPP BMPs help protect 6. ADDITIONAL REQUIREMENTS 21 Packet Pg. 110 2.4.c the site from concentrated (i.e., erosive) flows. General Construction SWPPP BMPs and their application for protection of LID BMPs in particular are summarized below. These BMPs must be considered for projects subject to Minimum Requirement No. 2 that are proposing to construct LID BMPs. Construction SWPPP BMP Application BMP C103: High Visibility Fence Use fencing to limit clearing; prevent disturbance of sensitive areas, their buffers, and other areas; limit construction traffic; and protect areas where marking with flagging may not provide adequate protection BMP C200: Interceptor Dike and Swale Use an interceptor dike and/or swale to intercept the runoff from unprotected areas and direct it to areas where erosion can be controlled BMP C201: Grass -Lined Channels Use grass lined channels where concentrated runoff may cause erosion and flooding of the site BMP C207: Check Dams Use check dams in swales or ditches to reduce the velocity and dissipate concentrated flow BMP C208: Triangular Silt Dike (TSD) Use triangular silt dikes as check dams, for perimeter protection, (Geotextile-Encased Check Dam) temporary soil stockpile protection, drop inlet protection, or as a temporary interceptor dike BMP C231: Brush Barrier Use brush barriers to decrease flow velocities and reduce transport of coarse sediment from overland flow BMP C233: Silt Fence Use silt fences to decrease flow velocities and reduce transport of sediment from overland flow BMP C234: Vegetated Strip Use vegetated strips to decrease flow velocities and reduce transport of sediment from overland flow 6.1.2 Additional Construction Techniques for LID BMPs In addition to the general Construction SWPPP BMPs presented in Section 6.1.1, this section outlines specific construction -phase techniques to protect LID BMPs. LID BMP protection is still a somewhat new and evolving practice, therefore the specific LID BMP protection measures outlined below are not explicitly called out in the SWMMWW. Rather, the techniques presented in this section supplement the Construction SWPPP BMPs presented above, and those presented in the SWMMWW Volume II. (Note these techniques can be applied to any site, not just those incorporating LID, but these techniques are particularly important for LID BMP protection.) Construction Site Planning and Sequencing Construction site planning and sequencing is a procedural BMP that is critical to successful installation and long-term operation of LID BMPs. Proper site planning and construction sequencing will minimize the impact of construction on permanent stormwater facilities by reducing the potential for soil erosion and compaction. Site planning and sequencing techniques to be used as practicable for protection of LID BMPs include: 22 6. ADDITIONAL REQUIREMENTS Packet Pg. 111 2.4.c Construction Site Planning and Sequencing Requirements Construction Site Planning and Sequencing Techniques Limit clearing and grading activities • Keep grading to a minimum by incorporating natural topographic depressions into the development. • Shape final lot grades and topographic features early (i.e., at the site development stage) where feasible. • Limit the amount of cut and fill in areas with permeable soils. • Limit clearing to road, utility, building pad, lawn areas, and the minimum amount of extra land necessary to maneuver machinery (e.g., a 10-foot perimeter around a building). Limit construction activity in areas • Clearly document —and plan to meet and walk through the designated for LID site with equipment operators prior to construction —to clarify construction boundaries, limits of disturbance, and construction activities in the vicinity of LID BMPs. • General/primary contractor must inform other sub -contractors of applicable LID BMP protection requirements. This is particularly important when working around permeable pavement. Limit clearing and grading during heavy • Time construction activities to start during the summer (lowest rainfall seasons precipitation) and end in the fall (when conditions are favorable for the establishment of vegetation), if feasible. Minimize the amount and time that graded • Complete construction and erosion control activities in one areas are left exposed section of the site before beginning activity in another section. Utilize permeable and nutrient rich soils • Preserve any portion of the site with permeable soils to promote infiltration of stormwater runoff. • Leave areas of rich topsoil in place, or if excavated, utilize elsewhere on the site to amend areas with sparse or nutrient deficient topsoil. Reduce impact of construction access roads • Reduce the number and size (width/length) of construction access roads. • Locate construction access roads in areas where future roads and utility corridors will be placed (unless utilizing permeable pavement). Promote sheet flow and minimize • Avoid grading that results in steep, continuous slopes, concentrated runoff especially in areas contributing runoff to LID BMPs. LID BMP activation • LID BMPs shall not begin operation until all erosion -causing project improvements (including use of access roads that may contribute sediment) are completed and all exposed ground surfaces are stabilized by revegetation or landscaping in upland areas potentially contributing runoff to the BMP. 0 CM 00 r U U w m 0 U c m E m a� R c `m 3 E `0 4- 0 c 0 c a� N N L IL c a� U I E 0 c m Q `m 3 E L 0 N 0 E w a� N a� I U r c m E t v cv r r Q c E t U 2 Q 6. ADDITIONAL REQUIREMENTS 23 Packet Pg. 112 2.4.c Activities During Construction Many common construction -phase activities pose a risk to LID BMPs. The following techniques will help minimize these impacts. Techniques to be used for protection of LID BMPs include: Erosion Control Requirements Erosion Control Techniques Protect native topsoil during the • Where practicable, protect areas of rich topsoil. If excavation is construction phase, and reuse on site necessary, stockpile native soils that can be used on the site after construction. • Stockpile materials in areas designated for clearing and grading (such as parking areas and future impervious roadways) and away from infiltration and other stormwater facilities. • Cover small stockpiles with weed barrier material that sheds moisture yet allows air transmission. Large stockpiles may need to be seeded and/or mulched. • Do not relocate topsoil or other material to areas where they can cover critical root zones, suffocate vegetation, or erode into adjacent streams. Use effective revegetation methods • Use native plant species adapted to the local environment. • Plant during late fall, winter, or early spring months when vegetation is likely to establish quickly and survive. • Utilize proper seedbed preparation. Fertilize and mulch to protect germinating plants. Apply 1 inch of compost topped with 2 inches of mulch. • Protect areas designated for revegetation from soil compaction by restricting heavy equipment. • Provide proper soil amendments where necessary (refer to SWMMWW, Volume V, Chapter 5, BMP T5.13 Post - Construction Soil Quality and Depth). Amend soil toward the end of construction. Once established, protect from compaction and erosion. • During storage, plants should be protected by solar screens when possible to prevent overexposure and excessive drying. Perform preconstruction, routine, and • Conduct a preconstruction inspection to verify that adequate postconstruction inspections barriers have been placed around vegetation retention areas, infiltration facilities (as needed), and structural controls are implemented properly. • Conduct routine inspections to verify that structural controls are being maintained and effectively protecting LID BMPs throughout construction. • Conduct a final inspection to verify that revegetation areas are stabilized and that permanent LID BMPs are in place and functioning ro erl . 24 6. ADDITIONAL REQUIREMENTS Packet Pg. 113 2.4.c 6.1.3 BMP-Specific Construction Techniques This section outlines construction -phase BMP protection techniques specific to categories of LID BMPs (e.g., infiltration and dispersion) as well as specific LID BMPs (permeable pavement, bioretention areas/rain gardens, and vegetated roofs). The BMP protection techniques presented previously in Section 6.1.2 are applicable to the overall construction site to help protect LID BMPs. The techniques outlined in this section are based on the specific BMP functions, targeting typical construction activities that pose a risk to individual BMPs. Infiltration and Dispersion Facility Construction Techniques It is critical that appropriate methods are used to protect infiltration and dispersion BMPs from compaction and sediment loading during construction. For infiltration facilities in particular, the subgrade soils must be protected from clogging and over -compaction to maintain the soil permeability and ensure BMP performance. Techniques for protection of infiltration and dispersion BMPs during various stages of construction are summarized below. Construction Stage Techniques for Protecting Infiltration and Dispersion Facilities Prior to construction • The infiltration/dispersion area shall be clearly identified (e.g., using flagging or high visibility fencing) and protected prior to construction to prevent compaction of underlying soils by vehicle traffic. • Develop a soil and vegetation management plan showing areas to be protected and restoration methods for disturbed areas before land clearing sta rts. • The Construction SWPPP sheets must outline construction sequencing that will protect the infiltration/dispersion area during construction. • Construction SWPPP BMPs and protection techniques identified in the previous sections shall be implemented as applicable. In particular, be sure to stabilize upslope construction areas (e.g., using silt fences, berms, mulch, or other Construction SWPPP BMPs) and minimize overland flow distances. Excavation • Excavation of infiltration/dispersion areas shall be performed by machinery operating adjacent to the BMP. No heavy equipment with narrow tracks, narrow tires, or large lugged high pressure tires shall be allowed on the infiltration/dispersion area footprint. • Where feasible, excavate infiltration/dispersion areas to final grade only after all disturbed areas in the upgradient project drainage area have been permanently stabilized. (If infiltration areas must be excavated before permanent site stabilization, initial excavation must be conducted to no less than 6 inches of the final elevation of the facility floor.) • Excavation of infiltration areas shall not be allowed during wet or saturated conditions. • The use of draglines and trackhoes should be considered for constructing infiltration and dispersion areas. • The bottom (and sidewalls if feasible) of an infiltration facility excavation must be raked or scarified to a minimum depth of 3 inches after final excavation to restore infiltration rates. • Scarify soil along the dispersion flow path if disturbed during construction. 6. ADDITIONAL REQUIREMENTS 25 Packet Pg. 114 2.4.c Construction Stage Techniques for Protecting Infiltration and Dispersion Facilities Sediment control . Bioretention, rain garden, and permeable pavement BMPs shall not be used as sediment control facilities, and all drainage shall be directed away from the BMP location after initial rough grading. Direct construction site flow away from the infiltration/dispersion area using applicable Construction SWPPP BMPs (e.g., temporary diversion swales). Permeable Pavement There are many potential applications and site scenarios where permeable pavement can be applied. The following techniques highlight the most broadly applicable techniques to be used to protect permeable pavement BMPs during construction. Refer to the previous section for construction protection methods that are applicable to all infiltration BMPs, as well as Sections 6.1.1 and 6.1.2 for general site protection measures. In addition to those techniques, the following techniques apply specifically for protection of permeable pavement during construction: • Use procedural BMPs to plan construction. For example, phase construction to minimize compaction, sedimentation, or structural damage to the permeable pavement. • Use physical Construction SWPPP BMPs and/or grade the site to avoid sediment laden runoff from reaching permeable pavements. • Place protective surfaces (e.g., waterproof tarps and steel plates) over any permeable pavement areas used for construction staging. %% • Do not drive sediment -laden construction equipment on the base material or pavement. Do not allow sediment -laden runoff on permeable pavements or base materials. • Once the pavement is finished and set, cover the pavement surface with plastic and geotextile to protect from other construction activities. Close and protect the pavement area until the site is permanently stabilized. • Incorporate measures to protect road subgrade from over compaction and sedimentation if permeable pavement roads are used for construction access. o Cover the aggregate base or pavement surface with protective geotextile fabric and protect fabric with steel plates or gravel. Gravel should only be used to protect the fabric placed over aggregate base. o Once construction is complete and the site is permanently stabilized, remove protective geotextile, clean, and complete pavement installation. Refer to the detailed permeable pavement BMP information in SWMMWW Volume V, Chapter 5, as well as City of Edmonds Standard Details for general permeable pavement construction criteria. 26 6. ADDITIONAL REQUIREMENTS Packet Pg. 115 2.4.c Bioretention Areas and Rain Gardens As with permeable pavements, there are many potential applications and site scenarios where bioretention and rain garden BMPs can be applied. The following techniques highlight the most broadly applicable techniques to be used to protect bioretention and rain garden BMPs during construction. Refer to the beginning of this section for construction protection methods that are applicable to all infiltration BMPs, as well as Sections 6.1.1 and 6.1.2 for general site protection measures. In addition to those techniques, the following techniques apply specifically for protection of bioretention and rain garden BMPs during construction: • Excavation: o If machinery must operate in the bioretention area for excavation, use lightweight, low ground -contact pressure equipment and rip the base at completion to scarify soil to a minimum of 12 inches. • Protect bioretention soil mix from compaction during construction o Do not place bioretention soil mix if saturated or during wet periods. o Check for compaction prior to planting. If compaction occurs, aerate the bioretention soil and then proceed to plant. Refer to the detailed bioretention and rain garden BMP information in SWMMWW Volume V, Chapter 7, as well as City of Edmonds Standard Details for general bioretention and rain garden construction criteria. YV Vegetated Roofs The following additional techniques apply for protection of vegetated roof facilities during construction: • Because of their location and complexity, vegetated roofs typically require more planning and coordination effort relative to ground -level landscaping. For new construction, a critical path approach is highly recommended to establish the sequence of tasks for construction of the vegetated roof system. • During construction, it is vitally important that the waterproof membrane be protected once installed. The waterproofing should be tested prior to placement of the growth media and other subsequent vegetated roof materials. Refer to the detailed vegetated roof BMP information in SWMMWW Volume V, for general construction criteria. 6. ADDITIONAL REQUIREMENTS 27 Packet Pg. 116 2.4.c 6.2 OFF -SITE ANALYSES AND DOCUMENTATION All projects subject to Minimum Requirement No. 4 shall submit as part of their Stormwater Site Plan an off -site analysis that assesses the potential off -site impacts of stormwater discharges. The following sections detail the analysis and documentation requirements for Category 1 and Category 2 projects. 6.2.1 Category 1 Projects Category 1 projects shall submit a qualitative analysis of potential off -site impacts of stormwater discharges for each upstream drainage system entering a site, and each downstream drainage system leaving a site. The upstream analysis shall identify and describe points where water enters the site. Any upstream contributing areas shall be identified and mapped in the project Stormwater Site Plan submittal. The downstream analysis shall extend from the project site to the receiving water, or up to one -quarter mile, whichever is less. In many cases, runoff that leaves a project site will enter the City's MS4 within one -quarter mile. In these instances, the project must evaluate and document downstream conditions up to and including runoff entry into the City's MS4. In addition, the project proponent shall consult with the City to determine whether the MS4 has any existing or anticipated capacity issues downstream of the proposed project. The qualitative analysis shall identify where and how stormwater runoff will leave the proposed development site, and describe conditions downstream of the site including any existing or anticipated future problem areas (e.g., spot flooding, property damage, erosion issues, capacity -limited drainage systems, etc.). The qualitative analysis must be sufficient for the City to evaluate whether the project has adequately identified potential impacts and whether proposed mitigation measures are supported by the analysis. Some "rough" quantitative analyses, which can be based on non -surveyed field data, may be necessary as part of the qualitative analysis to adequately describe or document the extent of observed problem areas. Note that any off -site field visits should be conducted during winter months and after significant precipitation events to identify seasonal issues such as flooding, capacity constraints, or surface seeps or other indicators of near surface groundwater. A quantitative analysis may also be required for any project where the project proponent or the City determines that a more thorough analysis is necessary to evaluate the off -site impacts or the capacity of the conveyance system (e.g., where there is evidence of a risk to downstream systems such as erosion, flooding, property damage, habitat damage, water quality degradation, or other related impacts). A quantitative analysis may include calculations and/or modeling analyses of on -site and off -site water quality, erosion, slope stability, and other drainage -related impacts that may be caused or aggravated by a proposed project. 6.2.2 Category 2 Projects All Category 2 projects shall submit a qualitative analysis of potential off -site impacts of stormwater discharges that extend downstream from the site to the receiving water. (If the ultimate discharge point is to Puget Sound via a culvert owned by BNSF Railway, the analysis must be followed through the drainage system all the way to Puget Sound.) A quantitative analysis may also be required for any project deemed to need additional downstream information or where the project engineer or the City determines that a quantitative analysis is necessary to evaluate the off -site impacts or the capacity of the conveyance system (e.g., where there are known capacity issues or where there is evidence of a risk to downstream 28 6. ADDITIONAL REQUIREMENTS Packet Pg. 117 2.4.c systems such as erosion, flooding, property damage, habitat damage, water quality degradation, or other related impacts). The qualitative analysis must be sufficient for the City to evaluate whether the project has adequately identified potential impacts and whether proposed mitigation measures are supported by the analysis. Some "rough" quantitative analysis, which can be based on non -surveyed field data, may be required at this stage. A downstream analysis of the project for a minimum of one -quarter of a mile is required. The analysis must also extend upstream to a point beyond any backwater effects caused by the project. The analysis must include field -inspection of all existing stormwater drainage systems downstream from the project and a determination of whether the capacity of the drainage system(s) is adequate to handle the existing flows, flows generated by the proposed project, and any overflow. Adequacy will be evaluated based on conveyance capacity, flooding problems, erosion damage or potential, amount of freeboard in channel and pipes, and storage potential within the system. Note that site visits should be conducted during winter months and after significant precipitation events to identify undocumented surface seeps or other indicators of near surface groundwater. See the end of this section for specific topics to be discussed in the qualitative analysis. When deemed necessary by the project engineer or required by the City, a quantitative analysis shall include the qualitative analysis describe above, as well as quantitative calculations and/or modeling analyses of on -site and off -site water quality, erosion, slope stability, and other drainage -related impacts that may be caused or aggravated by a proposed project. Measures for preventing impacts and for not aggravating existing impacts shall also be identified. ("Aggravating existing impacts" means increasing the frequency of occurrence and/or severity of an impact.) The analysis shall document how temporary and permanent flow control and water quality control measures identified in the Stormwater Site Plan will mitigate the potential to create new problems or aggravate existing conditions. In many cases, design of flow control and water quality systems according to the procedures contained in this Addendum and the SWMMWW will be adequate demonstration of mitigation. However, upon review of this analysis and the severity of an existing problem, the City may require more detailed analysis and/or additional mitigation measures. In general, all existing and proposed off -site surface water conveyance systems shall be sized to convey flows without surcharging the City's storm system (or BNSF culverts under the railroad tracks, if applicable). Both the qualitative analysis and the quantitative analyses (when required) shall include descriptions and/or analyses of the following items. The descriptions shall identify existing or potential problem areas, and whether adequate mitigation can be identified (or whether more detailed quantitative analysis is necessary). References to other Stormwater Site Plan sections (e.g., facility sizing, conveyance, attachments and appendices, etc.) are encouraged to reduce plan redundancy, as long as all of the required Stormwater Site Plan issues are clearly presented: • Describe the drainage system between the site and the receiving surface waters. Provide information on pipe sizes, channel characteristics, and drainage structures. Describe emergency services located along the flow path (e.g., fire/police stations, hospitals). Describe environmentally sensitive areas, such as wetlands, etc. • Describe the upstream drainage tributary to the project. Describe any bypass drainage from the project which will not be controlled. • The bulk of the analysis shall focus on highlights of important considerations from the project overview and off -site analysis sections related to the drainage system and potential problems or concerns. Existing and potential impacts to be evaluated and mitigated shall include, but not be limited to: 6. ADDITIONAL REQUIREMENTS 29 Packet Pg. 118 2.4.c O Conveyance system capacity issues. o Flooding or bank overtopping. o Upland erosion impacts, including slope stability and landslide hazards. O Stream channel erosion (at the outfall location and to the downstream limit of analysis). O Violations of surface water quality standards as identified in a Basin Plan or a TMDL/Water Cleanup Plan (e.g., for Lake Ballinger). O For each existing or potential problem, document: the magnitude of damage caused by the problem, the general frequency and duration, current mitigation of the problem (if any), the likely or possible cause of the problem, and whether the project is likely to aggravate the problem or create a new one. • Determine whether the project is within any other critical areas or their buffers as defined in ECDC, and whether any additional requirements apply. • All areas pertinent to the analyses such as site boundaries, study area boundaries, streets and prominent features, downstream flow path, potential/existing problems, etc. shall be keyed to features shown on the project map(s). 6.3 DESIGN REQUIREMENTS FOR DETENTION VAULTS AND PIPES T This section includes design requirements and associated information for detention vaults and detention pipes. The focus of this section is on the use of detention vaults and pipes to meet Minimum Requirement No. 5. For other design applications (e.g., to meet Minimum Requirement No. 7), designers must refer to the SWMMWW. For Category 1 and 2 projects that must comply with Minimum Requirement No. 5, the final option that is available for roofs and other hard surfaces under List No. 1 and List No. 2 (per ECDC 18.30.060.D.5 [d] or [e]) is the use of detention vaults or detention pipes. When using detention vaults or pipes to comply with Minimum Requirement No. 5 using List No. 1 or List No. 2 in the City of Edmonds, the following requirements apply. Note that if the project is required to construct a flow control facility to comply with Minimum Requirement No. 7 (per ECDC 18.30.060.D.7), a detention vault is not required to be installed to meet Minimum Requirement No. 5. The City may waive the requirement to install a detention vault or pipe if the downstream analysis in Minimum Requirement No. 4, or available City data indicate that peak flow control is not beneficial. Note that this exemption is rare and most similar to the direct discharge exemption in SWMMWW; qualifying for this exception will require unique site circumstances and may require additional information or calculations from the applicant to demonstrate lack of benefit. It shall not be applied to any site which discharges, direct or indirectly, to a stream, creek, wetland, or floodplain. 30 6. ADDITIONAL REQUIREMENTS Packet Pg. 119 2.4.c 6.3.1 Sizing & Design The City has created simplified sizing techniques for detention vaults and pipes for use in complying with Minimum Requirement No. 5. The sizing calculations and requirements presented below are designed to optimize detention facility functions relative to peak flow control as well as runoff "volume managed." Volume managed is a measure of the difference between facility inflow and outflow rates, and is evaluated using continuous simulation hydrologic modeling by comparing inflow and outflow over the entire continuous simulation. Volume managed represents an estimate of the amount of the storm flow that is attenuated (or removed, for facilities that utilize infiltration) by the flow control facility. To comply with Minimum Requirement No. 5, detention vaults or pipes must be installed for any site impervious surfaces totaling greater than or equal to 1,000 square feet that are not managed by other On - Site Stormwater Management BMPs. This includes areas from multiple types of surfaces listed under the list options in Minimum Requirement No. 5. For example, if unmanaged flows from roofs plus driveway areas exceed 1,000 square feet and runoff from both surfaces can be routed to a single vault, a vault shall be installed. In addition, projects may elect to route "managed" flows to the vault if desired (e.g., where runoff from an installed On -Site Stormwater Management BMPs cannot be easily separated from runoff drainage to the vault.) In this scenario, no upsizing of the vault is required for the "managed" areas. Only the unmanaged surfaces need to be included in the sizing calculations below. The City of Edmonds has developed standards specifically for vaults and pipes used to meet Minimum Requirement No. 5 only. See City standard detail SD-651 for detention tank requirements specific to minimum Requirement #5; this detail shall be completed with design information and included with any plan set proposing detention under Minimum Requirement #5. For compliance with Minimum Requirement No. 7, SWMMWW Volume V, Chapter 12 requirements apply. For vaults with contributing areas greater than or equal to 1,000 square feet the following sizing requirements apply: • Orifice size shall be 0.5 inches • Vault interior bottom area = 2 percent of contributing surface area • Vault minimum active storage depth = 3.0 feet 6.4 UNDERGROUND INJECTION CONTROLS With each update to the SWMMWW, the Department of Ecology continues to emphasize the importance of maximizing the use of infiltration for stormwater runoff control. Given the heavy emphasis on infiltration in the SWMMWW, and thus ECDC 18.30 and this Addendum, it is important to be aware of related requirements for Underground Injection Controls (UICs). In certain situations, BMPs that rely on infiltration are classified as UICs and may be regulated by Ecology under the UIC Program (Washington Administrative Code [WAC] 173 218). For more information on UICs, see SWMMWW Volume I, Chapter 4 (UIC Program). 6. ADDITIONAL REQUIREMENTS 31 Packet Pg. 120 2.4.c 0 CM Co r U a V W d O U r c 0 E 0 tm cv c L d 3 E L O 4- 0 r_ O N L a c a� U I E 7 C d Q L d 3 E L O Cl) N C O E W N N N I U r c a) E t v cv r r Q c O E t u 2 Q 32 6. ADDITIONAL REQUIREMENTS Packet Pg. 121 2.4.c 7 SUBMITTAL REQUIREMENTS Stormwater Site Plans are required for all projects subject to Minimum Requirement No. 1 — Preparation of Stormwater Site Plans (as well as for preparation of a Construction SWPPP, in accordance with Minimum Requirement No. 2), as outlined in Chapter 3 and ECDC 18.30.060.C. This chapter summarizes the requirements for submittals of stormwater plans, reports, and other documents for review by the City of Edmonds. As noted in Section 5.1, Stormwater Site Plans shall be prepared in accordance with Chapter 3 of Volume 1 of the SWMMWW. However, the City of Edmonds has developed checklists to facilitate compliance with Minimum Requirement No. 1 (and thus project submittal and review). This Addendum includes a summary of core submittal requirements for Category 1 and Category 2 projects as Checklists 1 and 2 in Appendix C. 7.1 CATEGORY 1 STORMWATER SITE PLANS Stormwater Site Plans for Category 1 projects must address Minimum Requirements No. 1 through No. 5 Detailed descriptions of submittal requirements are provided in Appendix C, Checklists 1 through 3. A schematic showing the components of a typical Category 1 project submittal is presented in Figure 7.1. Typical Category 1 Stormwater Site Plan Components Site Development Drawings and Reports and Construction SWPPP Drawings Documentation (i.e., construction drawings) Stormwater Site Plan Report, Supporting Documents, and Calculations Soils Report Construction SWPPP Narrative Establishment of Maintenance Covenant Appendices Figure 7.1. Typical Category 1 Stormwater Site Plan Components. 7.2 CATEGORY 2 STORMWATER SITE PLANS Stormwater Site Plans for Category 2 projects include the full submittal package meeting all minimum requirements. The Category 2 Stormwater Site Plan submittal package includes the following 7. SUBMITTAL REQUIREMENTS 33 Packet Pg. 122 2.4.c components: Stormwater Site Plan Report, Site Development Drawings, Soils Report, Construction SWPPP, Operations and Maintenance Manual, Maintenance Covenant, and any plan appendices. A schematic showing the components of a typical Category 2 Stormwater Site Plan submittal package is presented in Figure 7.2. The Construction SWPPP consists of two parts: a narrative report and drawings, which should be included in the plan set with the other Site Development Drawings. Detailed descriptions of submittal requirements are provided in Appendix C, Checklist 2. Typical Category 2 Stormwater Site Plan Components Site Development Drawings Reports and (i.e., construction drawings) Documentation Stormwater Site Plan Report, General Drawings Supporting Documents, and Calculations Construction SWPPP Drawings Soils Report Grading/Earthwork Drawings Construction SWPPP Narrative Plan/Profile Drawings Operation and Maintenance Manual Detail Drawings Establishment of Maintenance Covenant Appendices Figure 7.2. Typical Category 2 Stormwater Site Plan Components. 34 7. SUBMITTAL REQUIREMENTS Packet Pg. 123 2.4.c Appendix A — On -Site Stormwater Management BMP Infeasibility Criteria Packet Pg. 124 2.4.c 0 CM Oo r U a V W d O U r c 0 E 0 tm cv c L d 3 E L O 4- 0 r_ O N L a c a� U I E 7 C d a L d 3 E L O Cl) N C O E W N N N I U r c a) E t v cv r r Q c O E t u 2 Q Packet Pg. 125 OCTOBER 2021 EDMONDS STORMWATER ADDENDUM 2.4.c Appendix B — Methods for Determining Design Infiltration Rates 9% j Packet Pg. 126 2.4.c 0 CM Oo r U a V W d O U r c 0 E 0 tm cv c L d 3 E L O 4- 0 r_ O N L a c a� U I E 7 C d a L d 3 E L O Cl) N C O E W N N N I U r c a) E t v cv r r Q c O E t u 2 Q Packet Pg. 127 OCTOBER 2021 EDMONDS STORMWATER ADDENDUM 2.4.c Appendix C — Checklists for Various Project Submittal, Review, and Field Procedure Elements Packet Pg. 128 2.4.c 0 CM Oo r U a V W d O U r c 0 E 0 tm cv c L d 3 E L O 4- 0 r_ O N L a c a� U I E 7 C d Q L d 3 E L O Cl) N C O E W N N N I U r c a) E t v cv r r Q c O E t u 2 Q Packet Pg. 129 2.4.c Appendix D — Design Checklists for the Main On -Site Stormwater Management BM Ps j Packet Pg. 130 2.4.c 0 CM Oo r U a V W d O U r c 0 E 0 tm cv c L d 3 E L O 4- 0 r_ O N L a c a� U I E 7 C d a L d 3 E L O Cl) N C O E W N N N I U r c a) E t v cv r r Q c O E t u 2 Q Packet Pg. 131 2.4.d ADDENDUM TO EDMONDS COMMUNITY DEVELOPMENT CODE CHAPTER 18.30 (EDMONDS STORMWATER ADDENDUM) J URe 8, 2October 2021 Packet Pg. 132 2.4.d Q Packet Pg. 133 ii NE 2017-OCTOBER 2021 2.4.d EDMONDS STORMWATER ADDENDUM CONTENTS 1 Introduction...............................................................................................................................1 2 How to Use this Addendum......................................................................................................3 2.1 SWMMWW Volume I......................................................................................................3 2.2 SWMMWW Volume II.....................................................................................................4 2.3 SWMMWW Volume III....................................................................................................4 2.4 SWMMWW Volume IV.................................................................................................54 2.5 SWMMWW Volume V.....................................................................................................5 2.6 Addendum Content Not Covered in the SWMMWW......................................................5 3 Applicability of the Minimum Requirements...........................................................................7 3.1 Thresholds and Applicability............................................................................................9 3.1.1 Additional Requirements for Road -Related Projects.........................................9 3.1.2 New Connections to the City's MS4..................................................................9 3.1.3 Comparisons to the SWMMWW.....................................................................10 4 Project Basin Location and Applicable Requirements.......................................................1344 4.1 Determining Downstream Receiving System(s).........................................................1344 4.2 Other Considerations...................................................................................................1444 5 Project Minimum Requirements.........................................................................................154-3- 5.1 Minimum Requirement No. 1 — Preparation of Stormwater Site Plans ...................... 154-3- 5.2 Minimum Requirement No. 2 — Construction Stormwater Pollution Prevention Plan 154-3- 5.3 Minimum Requirement No. 3 — Source Control of Pollution ..................................... 154-3- 5.4 Minimum Requirement No. 4 — Preservation of Natural Drainage Systems and Outfalls........................................................................................................................164-4 5.5 Minimum Requirement No. 5 — On -Site Stormwater Management ............................174-5 5.6 Minimum Requirement No. 6 — Runoff Treatment.....................................................194-7 5.6.1 Edmonds -Specific Oil and Floatables Control.............................................204-9 5.7 Minimum Requirement No. 7 — Flow Control............................................................204-8 5.8 Minimum Requirement No. 8 — Wetland Protection...................................................214-8 5.9 Minimum Requirement No. 9 — Operation and Maintenance.....................................214} 6 Additional Requirements....................................................................................................2324 6.1 Protection of LID Facilities During Construction....................................................... 23-24 6.1.1 General Erosion and Sediment Control BMPs Applicable to LID...............23-24 6.1.2 Additional Construction Techniques for LID BMPs....................................2422 edmondsstormwateraddendum 2022 redlines _ TABLE OF CONTENTS Packet Pg. 134 EDMONDS STORMWATER ADDENDUM 2.4.d 11 INE'=7OCTOBER 2021 6.1.3 BMP-Specific Construction Techniques......................................................2725 6.2 Off -Site Analyses and Documentation........................................................................302-9 6.2.1 Category 1 Projects.......................................................................................302-9 6.2.2 Category 2 Projects.......................................................................................302-8. 6.3 Design Requirements for Detention Vaults and Pipes................................................3230 6.3.1 Sizing & Design............................................................................................3334 6.4 Underground Injection Controls..................................................................................3434 7 Submittal Requirements......................................................................................................353-3 7.1 Category 1 Stormwater Site Plans...............................................................................3534 7.2 Category 2 Stormwater Site Plans...............................................................................353-3 APPENDICES Appendix A — On -Site Stormwater Management BMP Infeasibility Criteria Appendix B — Methods for Determining Design Infiltration Rates Appendix C — Checklists for Various Project Submittal, Review, and Field Procedure Elements Appendix D — Design Checklists for the Main On -Site Stormwater Management BMPs LIST OF FIGURES Figure 3.1. Flow Chart for Determining Requirements for Development.................................8 Figure 7.1. Typical Category 1 Stormwater Site Plan Components....................................3534 Figure 7.2. Typical Category 2 Stormwater Site Plan Components . ................................... 363-2 H TABLE OF CONTENTS zz* edmondsstormwateraddendum 2022 redlin 115 05994 000_ cx Packet Pg. 135 2.4.d 1 INTRODUCTION This Edmonds Stormwater Addendum (Addendum) provides direction for implementing the City of Edmonds Community Development Code (ECDC) Chapter 18.30, Stormwater Management. The City of Edmonds is required to regulate stormwater discharges to the municipal stormwater system and to waters of the state, in compliance with the Western Washington Phase II National Pollutant Discharge Elimination System (NPDES) Municipal Stormwater Permit (the Permit). Under the Permit, the City must establish and apply the minimum requirements specified in the Permit and provide design guidance for stormwater quality and quantity control for development projects in Edmonds. Through ECDC Chapter 18.30 and this Addendum, the City is complying with federal requirements under the Clean Water Act and the Permit. This Addendum is organized into 7 chapters, briefly summarized below: • Chapter 2 — How to Use this Addendum includes information on how to use the Addendum in conjunction with the ECDC and Ecology's 20142019 Stormwater Management Manual for Western Washington (SWMMWW), and to clarify for users where the ECDC, SWMMWW, or Addendum apply. • Chapter 3 — Applicability of the Minimum Requirements includes details on the thresholds that determine the applicability of the minimum requirements to different projects. This information is based on SWMMWW Volume I, Section 2:43.3, but has been updated to reflect the specific requirements of ECDC 18.30. Chapter 3 also includes a brief summary of how ECDC 18.30.060 compares to the SWMMWW (regarding applicability of the minimum requirements). • Chapter 4 —Project Basin Locations and Applicable Requirements describes downstream receiving waterbodies and/or drainage systems in the city, which will affect how the minimum requirements apply to a given project (primarily Minimum Requirements No. 5, No. 6, and No. 7). Chapter 4 also includes a brief discussion of the unique soil and topographical conditions in the City of Edmonds. • Chapter 5 —Project Minimum Requirements highlights the primary differences between the minimum requirements presented in the SWMMWW and those in the ECDC and provides additional details and guidance to help projects comply with each minimum requirement. • Chapter 6 — Additional Requirements includes additional information on City -specific requirements that are not fully described in the SWMMWW or ECDC. Specific topics include: 1. Additional requirements pertaining to Construction Stormwater Pollution Prevention Plans (SWPPPs) Element No. 13 — Protect Low Impact Development (LID) Best Management Practices (BMPs) 2. Details on the off -site analyses and documentation required to comply with Minimum Requirement No. 4, Preservation of Natural Drainage Systems and Outfalls 1. INTRODUCTION 1 Packet Pg. 136 2.4.d 3. Design requirements for detention vaults and pipes when used to meet Minimum Requirement No. 5 4. Information on Underground Injection Controls (UICs) • Chapter 7 — Submittal Requirements summarizes the process and requirements for preparing project submittals that meet the requirements of the SWMMWW, the ECDC, and this Addendum. The appendices included in this Addendum provide additional background information and requirements related to stormwater management in the city. (Also note that there are several additional pertinent appendices within the SWMMWW that are adopted by reference.) The following City -specific appendices are included in this Addendum: • Appendix A — On -Site Stormwater Management BMP Infeasibility Criteria • Appendix B — Methods for Determining BMP Design Infiltration Rates • Appendix C — Checklists for Various Project Submittal, Review, and Field Procedure Elements o Checklist 1 — Category 1 Stormwater Site Plans o Checklist 2 — Category 2 Stormwater Site Plans o Checklist 3 — Construction SWPPP Drawings and Report o Checklist 4 — Methods for Determining Infiltration Rates o Checklist 5 — Field and Design Procedures for Bioretention, Permeable Pavement, Rain Gardens, and Downspout Infiltration Systems o Checklist 6 — Procedures for Infiltration Trenches and Basins • Appendix D — Design Checklists for the Main On -Site Stormwater Management BMPs o Checklist 7 — Post -Construction Soil Quality and Depth o Checklist 8 — Sheet Flow Dispersion o Checklist 9 — Concentrated Flow Dispersion o Checklist 10 — Bioretention Cells, Swales, and Planter Boxes o Checklist 11 — Permeable Paving o Checklist 12 — Rain Gardens o Checklist 13 — Downspout Infiltration o Checklist 14 — Downspout Dispersion o Checklist 15 — Perforated Stub -out Connections 2 1. INTRODUCTION Packet Pg. 137 2.4.d 2 HOW TO USE THIS ADDENDUM Review ECDC Chapter 18.30.030 and 18.30.040 to determine if the City's Stormwater Code and this Addendum apply to your project. Review the definitions section of ECDC Chapter 18.30.10 (and if necessary the Glossary in SWMMWW Volume I, Appendix G for clarification on terminology used in ECDC Chapter 18.30 and this Addendum. As per ECDC Chapter 18.30.60, the stormwater management requirements in the City of Edmonds — including but not limited to thresholds, definitions, minimum requirements, adjustment and variance criteria, and exceptions to these requirements — shall be governed by the 20142019 SWMMWW, with additional requirements and modifications as outlined in the provisions of ECDC Chapter 18.30 and this Addendum. Project proponents must review ECDC 18.30 (18.30.060 in particular) and this Addendum to identify how the City's requirements and the requirements of the SWMMWW apply to a given project. In the event of inconsistencies between the various provisions, the more stringent provisions shall apply, unless otherwise approved by the City. Where requirements in this Addendum are also covered in any other law, ordinance, resolution, rule, or regulation of any kind (i.e., outside of ECDC Chapter 18.30), the more restrictive requirement shall govern, unless otherwise approved by the City. This Addendum includes information to supplement or elaborate on the guidelines and requirements outlined in ECDC Chapter 18.30 and the SWMMWW. To highlight for Addendum users where the ECDC, SWMMWW, or Addendum apply, the following sections outline the general applicability of each document, summarized according to the organization of the SWMMWW. Note however that the SWMMWW is not always written in a manner that is suitable as a municipal regulatory tool, therefore there are known overlaps among the ECDC, SWMMWW, and Addendum. As such, this section is only intended to be a guide, not a definitive resource on SWMMWW applicability. When questions or potential inconsistencies arise, project proponents should contact the City for clarification and interpretation. 2.1 SWMMWW VOLUME I Chapter 1 — Introduction : Adopted in its entirety. • Chapter 2 Relationship of This Manual to Permits. Requirements, and Programs: Adopted in its entire . Chapter 2-3 —Minimum Requirements for New Development and Redevelopment_- Users should refer first to ECDC Chapter 18.30.60 and this Addendum. Note that some portions of ECDC 18.30.60 refer back to the SWMMWW as well as specific sections of this Addendum. o In addition, note dia4 for all minimum requirements that require flow modeling, unless otherwise specified, all continuous modeling shall be performed using the "Puget East 36" precipitation time series, consisting of a 158-year precipitation and evaporation time series that are representative of the climatic conditions in the City of Edmonds. This time series is available in WWHM241-2 (select "Use WS-DOT data") and MGSFlood (Extended Timeseries menu). 2. HOW TO USE THIS ADDENDUM 3 Packet Pg. 138 2.4.d o In addition, ECDC 18.30 includes an additional "retro-fit" specific to Minimum Requirement #5: see ECDC 18.30.060.D.5.b.i. Chapter- 3 apply to pr-oj eets in Edmonds, btA Chaptef 7 of this AddeRdufli has been er-eated Plans, Gity as well as additional speeifie stibmittal • • Chapter 4 — UIC Program: Adopted in its entirety. All UICs within Edmonds shall comply with the applicable requirements of this section. • Appendices —Use Appendix G for the SWMMWW only and refer to ECDC Chapter 18.30.10 for ECDC definitions. 2.2 SWMMWW VOLUME II • SWMMWW Volume II is adopted in its entirety. o In addition, this Addendum includes supplemental information to support compliance with SWMMWW Minimum Requirement No. 2, new Element No. 13 — Protect Low Impact Development BMPs. See Chapter 6. 2.3 SWMMWW VOLUME III .Chapter 1 — Choosing you BMPs: Chapter adopted in its entirety. o The infeasibility criteria typically are included within the specific BMP descriptions in the SWMMWW, but are summarized in Appendix A for clarity and ease of use. Appendix A also includes additional BMP infeasibility criteria that are specific to the City of Edmonds, and not necessarily included in the 2014 SWMMWW. o In addition, ECDC 18.30 adds detention to the list of BMPs to be considered under minimum requirement #5; see ECDC 18.30.060.D.5. •in addition, note that Chapter- 6 of this Addendum ineludes infefma4iea to supplement the andChapter 2 — Modelling Your BMPs: Chapter adopted in its entirety. o In addition, Checklist 8 thru 15 of this Addendum include checklists for desi rg iing BMPs. • Chapter 3 — Preparation of Stormwater Site Plans: Refer first to Chapter 7 of this Addendum, and associated Appendix C, Checklists 1 through 3. The requirements of SWMMWW Volume III, Chapter 3 apply to projects in Edmonds, but Chapter 7 of this Addendum has been created to 4 2. HOW TO USE THIS ADDENDUM Packet Pg. 139 2.4.d facilitate compliance with both the SWMMWW requirements for preparation of Stormwater Site Plans, as well as additional City -specific submittal requirements. 2.4 SWMMWW VOLUME IV • SWMMWW Volume IV is adopted in its entirety. 2.5 SWMMWW VOLUME V • SWMMWW Volume V is adopted in its entirety. o In addition, this Addendum includes supplemental information to support determination of On -Site Stormwater Management BMP infeasibility. Specifically, Appendix A of this Addendum summarizes infeasibility criteria that apply to each BMP (to be used in complying with Minimum Requirement No. 5). The infeasibility criteria typically are included within the specific BMP descriptions in the SWMMWW, but are summarized in Appendix A for clarity and ease of use. Appendix A also includes additional BMP infeasibility criteria that are specific to the City of Edmonds, and not necessarily included in the 20142019 SWMMWW. Where there are differences between the SWMMWW and Appendix A, the requirements in Appendix A shall apply unless otherwise approved by the City. o In addition, this Addendum include design requirements for detention tanks and vaults to meet the Edmonds -specific application of a detention as a BMP for Minimum Requirement #5 in Section 6.3. o In addition, ECDC 18.30 includes a "retrofit" provision under Minimum Requirement #5 which requires mitigating a portion of existingunmitigated nmitigated hard surfaces to remain on a project site; see ECDC 18.30.060.D.5.b.i 2.6 ADDENDUM CONTENT NOT COVERED IN THE • Note that in addition to the items included in Sections 2.1 through 2.5 above, this Addendum includes extensive information that is unique to the City and not tied to a specific SWMMWW volume or issue. Therefore, in addition to the notes above, users must review all of this Addendum and ECDC 18.30 for applicable requirements. This includes the Appendices and checklists included in this Addendum (particularly the BMP design checklists), which contain City -specific design, procedural, and submittal requirements that may not be reflected in the SWMMWW or ECDC. • In addition, as noted in Section 2.1 above, unless otherwise specified, all continuous modeling shall be performed using the "Puget East 36" precipitation time series, consisting of a 158-year precipitation and evaporation time series that are representative of the climatic conditions in the City of Edmonds. This time series is available in WWHM2412 (select "Use WS-DOT data") and MGSFlood (Extended Timeseries menu). 2. HOW TO USE THIS ADDENDUM 5 Packet Pg. 140 2.4.d • The use of corrugated metal pipe within Edmonds is prohibit on both private and public properties storm drain conveyance and /or BMPs (i.e. detention tanks). d c� a 0 M co U W d O V r C d E d m C R L d m 3 E L O cn 4- 0 O d L a m c m i E c m Q L m 3 E L O cn O E W d E t V Q E ci Q 6 2. HOW TO USE THIS ADDENDUM Packet Pg. 141 2.4.d 3 APPLICABILITY OF THE MINIMUM REQUIREMENTS This chapter is based on SWMMWW Volume I, Section 2.4, however the content below has been updated to reflect the specific requirements of ECDC 18.30. Project proponents must review ECDC 18.30 in detail. The following provides additional information and direction on the thresholds and applicability of minimum requirements outlined in ECDC 18.30.060. Project proponents must be aware that not all of the minimum requirements apply to every development project. The applicability varies depending on the project type and size. This chapter summarizes thresholds that determine the applicability of the minimum requirements to different projects. Review ECDC 18.30.060 and use the flow chart in Figure 3.1 to determine which of the minimum requirements apply to your project. (The minimum requirements themselves are provided in 18.30.060.D and are summarized in Chapter 5 of this Addendum). The thresholds described below and in Figure 3.1 are to be determined at the time of application for a subdivision, plat, short plat, building permit, or other construction permit. For projects involving only land disturbing activities, (e.g., clearing or grading), the thresholds apply at the time of application for the permit allowing or authorizing that activity. 3. APPLICABILITY OF THE MINIMUM REQUIREMENTS 7 Packet Pg. 142 2.4.d Does the project result in 2,000 square feet, or greater, of new plus replaced hard surface area? OR Does the land disturbing activity total 7,000 square feet or greater? Yes No Minimum Requirements No. 1 through 5 apply I Minimum Requirement No. 2 applies Next Question Does the project add 5,000 square feet or more of new plus replaced hard surfaces? OR Convert 0.75 acres or more of vegetation to lawn or landscaped areas? OR Convert 2.5 acres or more of native vegetation to pasture? No Yes No Is this a road related project? All Minimum Requirements apply to the new and replaced Yes hard surfaces and converted vegetation areas. All Minimum Requirements apply to the new hard surfaces and converted vegetation areas. Yes Does the project add 5,000 square feet or No more of new hard surfaces? Yes Do new hard surfaces add 50% or more to the existing hard surfaces within the project limits? No Figure 3.1. Flow Chart for Determining Requirements for Development. No additional requirements. 8 3. APPLICABILITY OF THE MINIMUM REQUIREMENTS Packet Pg. 143 2.4.d 3.1 THRESHOLDS AND APPLICABILITY All development shall be required to comply with Minimum Requirement No. 2. The following Category 1 project sites shall comply with Minimum Requirements No. 1 through No. 5: • Results in 2,000 square feet, or greater, of new plus replaced hard surface area, or • Have land disturbing activity of 7,000 square feet or greater. The following Category 2 project sites shall comply with Minimum Requirements No. 1 through No. 9: • Results in 5,000 square feet or more of new plus replaced hard surfaces, or • Converts 0.75 acres, or more, of vegetation to lawn or landscaped areas, or • Converts 2.5 acres, or more, of native vegetation to pasture. 3.1.1 Additional Requirements for Road -Related Projects For road -related projects, runoff from the new hard surfaces (including pavement, shoulders, curbs, and sidewalks) and the converted vegetation areas shall meet all the minimum requirements if the new hard surfaces total 5,000 square feet or more. In addition, if the new hard surfaces total 5,000 square feet or more and total 50 percent or more of the existing hard surfaces within the project limits, runoff from the new and replaced hard surfaces and the converted vegetation areas shall meet all the minimum requirements. The project limits shall be defined by the length of the project and the width of the right-of- way. 3.1.2 New Connections to the City's MS4 When a property owner proposes a new connection to the City's Municipal Separate Storm Sewer System (MS4), and the situation either 1) does not exceed the Category 1 or Category 2 thresholds above, or 2) does not involve activity that meets the definition of development, the following applies: • Sites that are not currently connected to the City's MS4 but wish to connect directly or indirectly to the City's MS4 may be allowed on a case -by -case basis, subject to City approval. • For sites that propose to drain greater than or equal to 2,000 square feet of hard surface area to the City's MS4, the project shall comply with the requirements of this chapter, treating all hard surfaces to be drained to the City system as new hard surfaces, unless applicant can demonstrate that the site will discharge in the same manner and quantities prior to the proposed project. Applicant shall account for natural dispersion and/or infiltration which may be occurring if these new hard surfaces area currently drain through pervious areas in their analysis.min4ffmm poses any risk to dowastfeam systems stieh as efesion, flooding, pr-epei4y damage, habita4 damage, ter- "alit), degn 4iea, E)r- other- r-eWed impaets. 3. APPLICABILITY OF THE MINIMUM REQUIREMENTS 9 Packet Pg. 144 2.4.d 3.1.3 Comparisons to the SWMMWW Project proponents must review ECDC 18.30 in detail, but the following notes are provided to help clarify how ECDC 18.30.060 compares to the SWMMWW regarding applicability of the minimum requirements (see Chapter 5 for additional details on the individual minimum requirements and how they differ from the SWMMWW): 1. ECDC 18.30 refers to "Category 1" projects and "Category 2" projects. See ECDC 18.30.060 for complete details, but in general: O Category 1 project sites result in 2,000 square feet, or greater, of new plus replaced hard surface area and shall comply with Minimum Requirements No. 1 through No. 5. O Category 2 project sites result in 5,000 square feet, or greater, of new plus replaced hard surface area and shall comply with Minimum Requirements No. 1 through No. 9. 2. ECDC 18.30 does not differentiate between new development and redevelopment. 3. Information regarding which surfaces each minimum requirement applies to (e.g., new hard surfaces, replaced hard surfaces, or both) is typically discussed under each minimum requirement as opposed to within the initial applicability section. 4In addition to item No. 3 above, ECDC 18.30.060.D.5.b includes a retrofit requirement for projects that discharge directly or indirectly to the City's MS4 and that contain existing hard surfaces that do not drain to an approved stormwater management facility. These projects are required to provide On -site Stormwater Management BMPs to manage a portion (a minimum of 25 percent) of those existing hard surfaces that will remain after project completion. See ECDC 18.30.060.D.5.b for complete details on this requirement. 45. ECDC 18.30.060.D.5 also adds detention as a BMP to be ^er�'�.onsidered for feasibility under Minimum Requirement #5 in additional to those in SWMMWW, see Section 6.3. 5-.6. As per the SWMMWW, for road -related projects, if the new hard surfaces total 5,000 square feet or more and total 50 percent or more of the existing hard surfaces within the project limits, runoff from the new and replaced hard surfaces shall meet all the minimum requirements. Otherwise, the minimum requirements only apply to the new hard surfaces (if the new hard surfaces total 5,000 square feet or more). Unlike the SWMMWW, non -road -related projects do not have to assess the valuation of the proposed improvements in order to determine the applicability of the minimum requirements. In general, once triggered by the applicable project area thresholds (see below and ECDC 18.30.060), the minimum requirements apply to both new and replaced hard surfaces. 7ECDC 18.30-.060 and this Addendum also includes requirements for new connections to the City's MS4, when the proposed connection does not involve activity that meets the definition of development. See the previous section of this Addendum for additional information on new connections. 8. ECDC 18.30 and this Addendum modify the flow modelling basin to be used in modelling, see Section 2.6. 9. ECDC 18.30 and this Addendum requires use of the phosphorus treatment menu within the Hall's Creek and Lake Ballinger basins; see Section 5.6. 6 10. Section 5.3, below, prohibits the use of corrugated metal piping (LCMP) within Edmonds. 10 3. APPLICABILITY OF THE MINIMUM REQUIREMENTS Packet Pg. 145 2.4.d Q 3. APPLICABILITY OF THE MINIMUM REQUIREMENTS 11 Packet Pg. 146 2.4.d Q Packet Pg. 147 2.4.d 4 PROJECT BASIN LOCATION AND APPLICABLE REQUIREMENTS 4.1 DETERMINING DOWNSTREAM RECEIVING SYSTEM(S) Broadly speaking, stormwater runoff in the City of Edmonds either travels west to Puget Sound (via a creek or piped system) or to the east to Lake Ballinger or Hall Creek, which discharges to Lake Ballinger. In addition to assessing the new and replaced hard surfaces and converted vegetation areas associated with a project, the minimum requirements (primarily Minimum Requirements No. 5, No. 6, and No. 7) can also vary depending on the project's downstream receiving waterbody and/or drainage system. The specific details of each minimum requirement are outlined in Chapter 5, but in general, projects should determine what type of system(s) their project site drains to early in the development process: The two primary systems to be aware of are described below. Note that these systems are not mutually exclusive: 1. Direct Discharge areas: Those site areas that discharge runoff directly to Puget Sound via a constructed conveyance system (e.g., pipe or ditch) without first entering a creek or other receiving water. (See Section 2.53.4.7 of Volume I of the SWMMWW for the full list of restrictions that must be met to qualify as a direct discharge.) 2. City of Edmonds Municipal Separate Storm Sewer System (MS4): Those site areas that discharge to the City's MS4 before ultimately discharging to a downstream receiving water (e.g., a creek, lake, or Puget Sound). See the City's NPDES Municipal Stormwater Permit for the complete MS4 definition, but this generally includes sites that discharge to a dedicated stormwater conveyance system (including roads with drainage systems, ditches, manmade channels, or storm drains) owned or operated by the City and that discharge to waters of Washington State (including creeks, lakes, ponds, wetlands, and Puget Sound). A map of watersheds in Edmonds is available via the Edmonds GIS Map that can be accessed on the City's website here: (<www.maps.edmondswa.gov>). (Note that the City's NIS4 is fet ide ti fie r City's S4+Direct Discharge Basins are those labeled "Puget Sound;" or "Puget Sound Piped_;"ef "Edmends x; ay." - Edmonds Way is known to have an overflow under certain conditions which creates a discharge to Edmonds Marsh (not considered man-made drainage course for the purposes of this exemption), and therefore the Edmonds Way basin shall not be considered a direct discharge basin. An applicant with site -specific information that is contrary to the basin designations shown in Figure B-1 can present this information to the Public Works Director (Director) or designee for a possible change in basin designation. The Director or designee will make a determination on any requests for a site -specific change in basin designation. 4. PROJECT BASIN TYPE AND APPLICABLE REQUIREMENTS 13 Packet Pg. 148 2.4.d 4.2 OTHER CONSIDERATIONS Edmonds is fortunate to be located adjacent to Puget Sound and possess topography that facilitates desirable views. The underlying soils and relatively steep slopes, however, complicate the application of stormwater management techniques. Prior to logging and subsequent development of the Edmonds area, trees and the forest duff layer above the soil surface (consisting primarily of needles, leaves, branches, bark, and stems in various stages of decomposition) covered the city. With logging came the elimination of the majority of the tree canopy and the duff layer, and with it the elimination of the water -holding capacity of the natural land cover. In the majority of the city, the soils that remain (after forest removal and subsequent development) consist of till or hard pan, which is much less effective at storing or absorbing rainwater. Although this Addendum and the SWMMWW place substantial emphasis on the use of infiltration and on -site stormwater management techniques, the soil regime in the City of Edmonds can make this goal challenging. It is therefore important that project sites thoroughly investigate and understand their soil conditions (as well as other site conditions such as slope, groundwater levels, etc.) before proceeding too far with the site stormwater design. See the submittal checklists in Appendix C (Checklists 1 through 3), BMP infeasibility criteria in Appendix A, and SWMMWW Chapter- 3-for additional details and requirements. In addition to challenging soil conditions, approximately 25 percent of the land area in the City of Edmonds has a slope of 15 percent or greater or is in an Earth Subsidence and Landslide Hazard Area (the Meadowdale area in the northernmost portion of the city). Geologic hazards in these areas can be increased when stormwater runoff from impervious surfaces percolates into the soil. As emphasized in the submittal checklists in Appendix C (Checklists 1 through 3), BMP infeasibility criteria in Appendix A, and SWMMWW Chapter 3; consideration of slopes in the project vicinity is a critical component of the site stormwater design. 44 FVJ 14 4. PROJECT BASIN TYPE AND APPLICABLE REQUIREMENTS Packet Pg. 149 2.4.d 5 PROJECT MINIMUM REQUIREMENTS This chapter should be used as a supplement to ECDC 18.30.060.13 and SWMMWW Volume I, Seetion 3 as it emphasizes the key differences between the minimum requirements outlined in the SWMMWW and those outlined in ECDC 18.30.060.D. Project proponents must still review ECDC 18.30.060.D in detail, but the following text provides additional information and direction on the minimum requirements outlined in ECDC 18.30.060.D. As noted previously in Chapter 4, once a given minimum requirement is triggered (per the thresholds in Chapter 3), the specifics of the minimum requirement may vary depending on the project downstream receiving waterbody and/or drainage system. 5.1 MINIMUM REQUIREMENT NO. 1 - PREPARATION OF STORMWATER SITE PLANS Stormwater Site Plans are required for all projects subject to Minimum Requirement No. 1, as outlined in Chapter 3 and ECDC 18.30.060.C. Stormwater Site Plans shall be prepared in accordance with Chapter 3 of Volume 4-III of the SWMMWW. However, because Chapter 3 of the SWMMWW includes extensive technical requirements, but does not explicitly specify how those requirements shall be consistently documented, submitted, and/or reviewed for a typical development project, the City of Edmonds has developed project checklists to facilitate compliance with this minimum requirement (and thus project submittal and review). Those checklists are introduced in Chapter 7 and provided in Appendix C, Checklists 1 through 3. 5.2 MINIMUM REQUIREMENT NO. 2 - CONSTRUCTION STORMWATER POLLUTION PREVENTION PLAN See ECDC 18.30.060.D.2. In addition, note that ECDC 18.30.060.D.2.d.i points to the SWMMWW Chapter -23, Section 2-.5--.23.4.2 for details on the requirements for Construction Stormwater Pollution Prevention Plans (SWPPPs), including the 13 Elements that must be reflected in the Construction SWPPP. See Chapter 6 for additional requirements pertaining to Construction SWPPP Element No. 13 — Protect Low Impact Development BMPs, which are not provided in the SWMMWW. 5.3 MINIMUM REQUIREMENT NO. 3 - SOURCE CONTROL OF POLLUTION See ECDC 18.30.060.D.3 and SWMMWW Volume IV. Note that all single-family residential projects shall, at a minimum, incorporate required BMPs from SWMMWW Volume IV, S411 — BMPs for Landscaping and Lawn/Vegetation Management. 5. PROJECT MINIMUM REQUIREMENTS 15 Packet Pg. 150 2.4.d Corrugated metal pipe (CMP) has been found to be a routine failure problem in Edmonds and a potential source of additional sediment in the Citysystem. For this reason, CMP pipe is not permitted within Edmonds on either pulic or private property or both conveyance storm pipe and for detention tanks. 5.4 MINIMUM REQUIREMENT NO. 4 - PRESERVATION OF NATURAL DRAINAGE SYSTEMS AND OUTFALLS See ECDC 18.30.060.D.4 and the content presented below. Although this minimum requirement is based on Minimum Requirement No. 4 in SWMMWW Volume I, Section 1-543.4.4, there are enough differences between the City's requirements and those in the SWMMWW that project proponents should not refer to the SWMMWW for Minimum Requirement No. 4. Only ECDC 18.30.060.D.3 and the following shall be required. To demonstrate compliance with this minimum requirement, all projects shall submit as part of their Stormwater Site Plan an off -site analysis that assesses the potential off -site impacts of stormwater discharges. (See the end of this section, and Chapter 6, for details on the requirements for analysis and documentation.) Natural drainage patterns shall be maintained, and discharges from the project site shall occur at the natural location, to the maximum extent practicable. The manner by which runoff is discharged from the project site must not cause a significant adverse impact to downstream receiving waters or down gradient properties. The discharge must have an identified overflow route that is safe and certain, and leads to the ultimate outfall location (such as a receiving water or municipal drainage system). All outfalls require energy dissipation. (Designs for outfall systems to protect against adverse impacts from concentrated runoff are included in SWMMWW Volume V, Chapter 41.) In addition, existing upstream flows must be accommodated without causing erosion or flooding impacts. Upstream drainage means drainage from adjacent property that enters the proposed project site (other than a defined natural channel). Upstream flows shall not be routed through the project's conveyance, treatment, or retention/detention systems, unless those systems are sized to control those flows. Upstream flows that are collected and routed through or around the site in a separate conveyance shall be dispersed at the downgradient property line, if feasible, or discharged at a project outfall (or outfalls) in a manner that does not violate the criteria below or cause the capacity of a conveyance system to be exceeded. Where no conveyance system exists at the adjacent downgradient property line and the discharge was previously unconcentrated flow or significantly lower concentrated flow, measures must be taken to prevent downgradient impacts. Drainage easements from downstream property owners may be needed and should be obtained prior to approval of engineering plans. For Category 2 projects only — where no conveyance system exists at the adjacent downstream property line and the natural (existing) discharge is unconcentrated, any runoff concentrated by the proposed project, including upstream drainage, must be discharged as follows: 1. If the 100-year peak discharge is less than or equal to 0.2 cfs (0.3 cfs using 15-minute time steps) under existing conditions and will remain less than or equal to 0.2 cfs under developed conditions, then the concentrated runoff may be discharged onto a rock pad or to any other system that serves to disperse flows. 2. If the 100-year peak discharge is between 0.2 and 0.5 cfs (or 0.75 cfs using 15-minute time steps) under existing conditions and will remain in that range under developed conditions, then the 16 5. PROJECT MINIMUM REQUIREMENTS Packet Pg. 151 2.4.d concentrated runoff may be discharged through a dispersal trench or other dispersal system, provided the applicant can demonstrate that there will be no significant adverse impact to downhill properties or drainage systems. 3. If the 100-year peak discharge is greater than 0.5 cfs for either existing or developed conditions, or if a significant adverse impact to downgradient properties or drainage systems is likely, then a conveyance system shall be provided to convey the concentrated runoff across the downstream properties to an acceptable discharge point (i.e., an enclosed drainage system or open drainage feature where concentrated runoff can be discharged without significant adverse impact). To demonstrate compliance with this minimum requirement, all projects shall submit as part of their Stormwater Site Plan an off -site analysis that assesses the potential off -site impacts of stormwater discharges. Off -site analyses shall assess upstream and downstream conditions, including the conveyance capacity and erosion potential in the downstream system. If a problem is found, mitigation is required to prevent worsening of that problem or to mitigate an existing flooding or erosion problem. The off -site analysis shall include, at a minimum, a qualitative analysis of each upstream drainage system entering a site, and each downstream drainage system leaving a site. A quantitative analysis may be required for any project deemed to need additional downstream information or where the project proponent or the City determines that a quantitative analysis is necessary to evaluate the off -site impacts or the capacity of the conveyance system (e.g., where there is evidence of a risk to downstream systems such as erosion, flooding, property damage, habitat damage, water quality degradation, or other related impacts). See Chapter 6 for additional details on off -site analyses and documentation. 5.5 MINIMUM REQUIREMENT NO. 5 - ON -SITE STORMWATER MANAGEMENT The City has made several additions and changes to the contents of Minimum Requirement No. 5 relative to the SWMMWW. Project proponents must review ECDC 18.30.060.D.5 in detail to ensure all City - specific requirements are addressed. This section of the Addendum provides a summary of the City - specific elements of Minimum Requirement No. 5. In addition, this Addendum includes several tools to support implementation of Minimum Requirement No. 5 and related requirements. These tools include: A summary of infeasibility criteria for all On -Site Stormwater Management BMPs (see Appendix A). These infeasibility criteria must be considered when evaluating the feasibility of On -Site Stormwater Management BMPs as part of List No. 1 or List No. 2. The infeasibility criteria are included within the specific BMP descriptions in the SWMMWW, but are summarized in Appendix A for clarity. Appendix A also includes additional BMP infeasibility criteria that are specific to the City of Edmonds, and not necessarily included in the 240442019 SWMMWW. 2. A summary of acceptable methods for determining BMP design infiltration rates (see Appendix B; and Appendix C, Checklist 4). Initial site infiltration rates may be determined either using field testing procedures, or the Soil Grain Size Analysis Method. These methods are described in detail in Appendix B. 5. PROJECT MINIMUM REQUIREMENTS 17 Packet Pg. 152 2.4.d A summary of site investigation and field and design procedures required for several of the On - Site Stormwater Management BMPs as well as for infiltration basins and trenches (see Appendix C, Checklists 5 and 6). The field and design procedures required to design and implement On -Site Stormwater Management BMPs can be considerable, and include issues such as determining infiltration rates, determining depth to groundwater or other impermeable layers, soils reporting requirements, etc. 4. Submittal checklists for Category 1 and Category 2 projects, including notes on project site, soil, and BMP design information that must be documented and submitted to the City to meet the City of Edmonds and SWMMWW requirements related to Minimum Requirement No. 5 (and other minimum requirements. See Appendix C, Checklists 1 through 3. 5. Design checklists for most of the On -Site Stormwater Management BMPs in List No. 1 and List No. 2 (see Appendix D). The applicability of Minimum Requirement No. 5 depends on the project type, project location, and the existing and proposed surfaces at the project site. See ECDC 18.30.060.D.5 for details, but in summary: Projects that drain directly or indirectly to the City's MS4 and that contain existing hard surfaces that do not drain to an approved stormwater management facility are required to provide On -Site Stormwater Management BMPs to manage a minimum of 25 percent of those existing hard surfaces that will remain after the project. The intent is to bring a portion of any existing, unmanaged surfaces up to current standards. If the 25 percent minimum is met, projects are not required to evaluate BMPs in priority order or document infeasibility for these existing surfaces (as per the subsequent project scenarios). 2. Similar to the SWMMWW, Category 1 project sites (project sites subject to Minimum Requirements No. 1 through No. 5) that discharge directly or indirectly to the City's MS4 shall either use On -Site Stormwater Management BMPs from List No. 1 (see ECDC 18.30.060.D.5.d) for all new plus replaced hard surfaces and land disturbed, or demonstrate compliance with the LID Performance Standard (See ECDC 18.30.060.D.5.c). Note that in the City of Edmonds, List No. 1 includes detention vaults or pipes as the final BMP option for roofs and other hard surfaces. See Chapter 6 for associated design requirements for detention vaults and pipes, including simplified sizing methods for meeting Minimum Requirement No. 5. (Note also that if the project is required to construct a flow control facility to comply with Minimum Requirement No. 7 (per ECDC 18.30.060.D.7), a detention vault or pipe is not required to be installed to meet Minimum Requirement No. 5.) Categor,2project sites (project sites subject to Minimum Requirements No. 1 through No. 9) are subject to similar requirements as Category 1 projects, but must use List No. 2 instead of List No. 1 (see ECDC 18.30.060.D.5.e). 4. Projects that discharge directly to Puget Sound through the City's MS4 (in accordance with the restrictions applicable to direct discharges to Puget Sound presented in Section 2.5.7 of Volume I of the SWMMWW) do not have to achieve the LID Performance Standard, and only have to evaluate a subset of the BMPs in List No. 1 or List No. 2. in addition, Edmonds Way Basi- (see the Edmonds GIS Map available on the City's website) n:mst demenstfate that the pr-qjeet's -post development 10 , and 100 year- r-eetifFeRee ifltel=val POWs W4 not exeeed 0.25 and 0.45 eubie feet per- seeend per- aer-e of impen4ous sur-faee area, r-espeetiv4y-. 5. Projects that do not drain directly or indirectly to the City's MS4 are required to either: 18 5. PROJECT MINIMUM REQUIREMENTS Packet Pg. 153 2.4.d o Discharge to the downstream private property (with approval) o Discharge runoff to an on -site system from List No. 1 (see in ECDC 18.30.060.D.5.d). ■ Sites located within earth subsidence and landslide hazard areas or their buffers are not required to evaluate BMPs in priority order or document infeasibility. However, a geotechnical design, analysis, and report by a geotechnical engineer is required. ■ For sites located outside earth subsidence and landslide hazard areas or their buffers, projects must meet applicable Category 1 or Category 2 project requirements for Minimum Requirement No. 5 (see ECDC 18.30.060.D.5.ii and ECDC 18.30.060.D.5.iii). o Project sites may pump on -site runoff to the City's MS4, with prior approval. a,,wast e ri, analysis will be .o ,,; oa ; in such cases, projects shall meet all provisions of ECDC 18.30 as they would drain to the MS4 in post project conditions. 6. Finally, the following guidance shall be used to help clarify the requirements in the SWMMWW specific to List No. 1 and No. 2. Where the SWMMWW and ECDC 18.30.060.D.5.d/e states that "for each surface, consider the BMPs in the order listed for that type of surface. Use the first BMP that is considered feasible. No other On -Site Stormwater Management BMP is necessary for that surface" the following clarifications are provided: o The goal of List No. 1 and List No. 2 is to manage 100 percent of each surface. If a project cannot manage 100 percent of a given surface with the first feasible BMP, a second BMP may be required to manage the remaining unmanaged area (depending on the size of the unmanaged area and the site -specific constraints). For example, where a roof surface drains to multiple downspouts around the perimeter of the structure, it is generally insufficient to only manage runoff that drains to a single downspout and to leave the remaining downspouts unmanaged (i.e., due to infeasibility considerations). 7. For BMPs without specific sizing criteria in this Addendum, single family residential projects under 2,000 SF of new plus replaced hard surfaces only, may use the simplified sizing per the included checklist for each BMP or per Volume V of SWMMWW to satisfy Minimum Requirement #5. However, such sizing methodology shall be assumed to generate an overflow and a piped or subsurface overflow connection is required for such BMPs unless otherwise waived by the City. 5.6 MINIMUM REQUIREMENT NO. 6 - RUNOFF TREATMENT See ECDC 18.30.060.D.6 for thresholds and core requirements. See the SWMMWW for additional information on complying with this minimum requirement. In particular, the following sections should be reviewed: • Volume I, Section2-.-S-.63.4.6 for details on treatment facility sizing • Volume I, Chapter 4 and Volume V, Chapters 2 and 3 for general BMP selection. Note also that phosphorus treatment is required for projects that drain to Hall Creek or Lake Ballinger. 5. PROJECT MINIMUM REQUIREMENTS 19 Packet Pg. 154 2.4.d 0 Volume V for design and maintenance requirements. 5.6.1 Edmonds -Specific Oil and Floatables Control In addition to the oil control requirements in the SWMMWW, all projects in the City of Edmonds not zoned as single-family residential that collect runoff from five or more parking spaces shall install floatable controls in catch basins (if another approved floatable control system is not employed). 5.7 MINIMUM REQUIREMENT NO. 7 — FLOW CONTROL See ECDC 18.30.060.D.7 for thresholds and core requirements. See the SWMMWW for additional information on complying with this minimum requirement (in particular, Volume I, Section 1-5-.73.4.7). Note that flow control in accordance with Minimum Requirement No. 7 is not required for projects that discharge directly to, or indirectly through the City's MS4 to Puget Sound (other minimum requirements still apply, including Minimum Requirement No. 6, as well as Minimum Requirement No. 5 and the Edmonds Way direct discharge requirements). See ECDC 18.30.060.D.5.b.iv and Section 2-.5-.73.4.7 of Volume I of the SWMMWW for additional restrictions applicable to direct discharges to Puget Sound. In addition, the following information may be useful in determining the applicability of Minimum Requirement No. 7, specifically per the 100-year flow frequency threshold outlined in ECDC 18.30.060.D.7.b.iii: Calculations to determine whether a project exceeds the 0.10 cubic feet per second (cfs), using a 1-hour time step (or 0.15 cfs using a 15-minute time step) increase in the 100-year recurrence interval flow must be performed individually for each project using an approved continuous simulation runoff model. The calculation will compare runoff in the post development site to the pre -development land cover. Pre - development, for this activity only, is the lower runoff of the pre project condition, or the site on July 6, 1977 (the effective date of the City's first drainage control ordinance). The unique site, soil, precipitation, and other project -specific factors will ultimately determine whether this threshold is exceeded. Nonetheless, the following general guidelines (based on hypothetical site designs) may be used to help identify the likelihood of this threshold being exceeded. The following land use changes are likely to exceed this threshold under certain conditions: • Converting approximately 5,000 square feet of forest to hard surface • Converting approximately 5,000 square feet of pasture to hard surface • Converting approximately 0.25 acres of forest to landscape surface • Converting approximately 1.25 acres of forest to pasture surfaces (in till soil conditions) 20 5. PROJECT MINIMUM REQUIREMENTS Packet Pg. 155 2.4.d 5.8 MINIMUM REQUIREMENT NO. 8 - WETLAND PROTECTION See ECDC 18.30.060.D.8 and SWMMWW Volume I, Section ''�3.4.8. See also SWMMWW Volume I, Appendix I-D-C . 5.9 MINIMUM REQUIREMENT NO. 9 - OPERATION AND MAINTENANCE See ECDC 18.30.060.D.9. See also the submittal checklists provided in Appendix C, Checklists 1 through 3 (also referenced previously as part of Minimum Requirements No. 1 and No. 5) for notes about submittal requirements related to the required operation and maintenance manual. !, I 5. PROJECT MINIMUM REQUIREMENTS 21 Packet Pg. 156 2.4.d Q Packet Pg. 157 2.4.d 6 ADDITIONAL REQUIREMENTS This chapter includes additional requirements that are either not included in the SWMMWW, or that are supplemental to the information provided in the SWMMWW. Specifically, this chapter addresses: 1. Additional requirements pertaining to Construction SWPPP Element No. 13 — Protect Low Impact Development BMPs (required in the SWMMWW, bttt not outlined in this level of detail) 2. Details on the off -site analyses and documentation required to comply with Minimum Requirement No. 4, Preservation of Natural Drainage Systems and Outfalls (City of Edmonds specific). 3. Design requirements for detention vaults and pipes when used to meet Minimum Requirement No. 5. 4. Information on Underground Injection Controls (UICs). 6.1 PROTECTION OF LID FACILITIES DURING CONSTRUCTION To ensure that LID stormwater facilities and BMPs will be fully functional after construction, it is important to protect these BMPs during construction activities. Protecting native soil and vegetation, minimizing soil compaction, and retaining the hydrologic function of LID BMPs during the site preparation and construction phases are some of the most important practices during the development process. The purpose of this section is to provide designers, builders, and inspectors with guidance and tools for meeting Minimum Requirement No. 2, Element No. 13 — Protect Low Impact Development BMPs. This section does not provide guidance on construction or design of LID BMPs (see SWMMWW Volume III and Volume V), or cover all Construction SWPPP practices (see SWMMWW Volume II), but rather focuses on how to most efficiently reduce impacts on LID BMPs specifically during construction. The practices specified in this section must be applied to protect LID BMPs, unless the given practice does not apply to the project site conditions or activities. 6.1.1 General Erosion and Sediment Control BMPs Applicable to LID Overall Construction Stormwater Pollution Prevention Plan (SWPPP) requirements are specified in Chapter 5, Minimum Requirement No. 2 and SWMMWW Volume II. In general, Construction SWPPP BMPs limit the impact of site disturbance, erosion, and sediment deposition during construction. Some Construction SWPPP BMPs focus on providing a physical barrier or deterrent to help minimize construction -related site disturbance and/or erosion, while other Construction SWPPP BMPs help protect 6. ADDITIONAL REQUIREMENTS 23 Packet Pg. 158 2.4.d the site from concentrated (i.e., erosive) flows. General Construction SWPPP BMPs and their application for protection of LID BMPs in particular are summarized below. These BMPs must be considered for projects subject to Minimum Requirement No. 2 that are proposing to construct LID BMPs. Construction SWPPP BMP Application BMP C103: High Visibility Fence Use fencing to limit clearing; prevent disturbance of sensitive areas, their buffers, and other areas; limit construction traffic; and protect areas where marking with flagging may not provide adequate protection BMP C200: Interceptor Dike and Swale Use an interceptor dike and/or swale to intercept the runoff from unprotected areas and direct it to areas where erosion can be controlled BMP C201: Grass -Lined Channels Use grass lined channels where concentrated runoff may cause erosion and flooding of the site BMP C207: Check Dams Use check dams in swales or ditches to reduce the velocity and dissipate concentrated flow BMP C208: Triangular Silt Dike (TSD) Use triangular silt dikes as check dams, for perimeter protection, (Geotextile-Encased Check Dam) temporary soil stockpile protection, drop inlet protection, or as a temporary interceptor dike BMP C231: Brush Barrier Use brush barriers to decrease flow velocities and reduce transport of coarse sediment from overland flow BMP C233: Silt Fence Use silt fences to decrease flow velocities and reduce transport of sediment from overland flow BMP C234: Vegetated Strip Use vegetated strips to decrease flow velocities and reduce transport of sediment from overland flow 6.1.2 Additional Construction Techniques for LID BMPs In addition to the general Construction SWPPP BMPs presented in Section 6.1.1, this section outlines specific construction -phase techniques to protect LID BMPs. LID BMP protection is still a somewhat new and evolving practice, therefore the specific LID BMP protection measures outlined below are not explicitly called out in the SWMMWW. Rather, the techniques presented in this section supplement the Construction SWPPP BMPs presented above, and those presented in the SWMMWW Volume II. (Note these techniques can be applied to any site, not just those incorporating LID, but these techniques are particularly important for LID BMP protection.) Construction Site Planning and Sequencing Construction site planning and sequencing is a procedural BMP that is critical to successful installation and long-term operation of LID BMPs. Proper site planning and construction sequencing will minimize the impact of construction on permanent stormwater facilities by reducing the potential for soil erosion and compaction. Site planning and sequencing techniques to be used as practicable for protection of LID BMPs include: 24 6. ADDITIONAL REQUIREMENTS Packet Pg. 159 2.4.d Construction Site Planning and Sequencing Requirements Construction Site Planning and Sequencing Techniques Limit clearing and grading activities • Keep grading to a minimum by incorporating natural topographic depressions into the development. • Shape final lot grades and topographic features early (i.e., at the site development stage) where feasible. • Limit the amount of cut and fill in areas with permeable soils. • Limit clearing to road, utility, building pad, lawn areas, and the minimum amount of extra land necessary to maneuver machinery (e.g., a 10-foot perimeter around a building). Limit construction activity in areas • Clearly document —and plan to meet and walk through the designated for LID site with equipment operators prior to construction —to clarify construction boundaries, limits of disturbance, and construction activities in the vicinity of LID BMPs. • General/primary contractor must inform other sub -contractors of applicable LID BMP protection requirements. This is particularly important when working around permeable pavement. Limit clearing and grading during heavy • Time construction activities to start during the summer (lowest rainfall seasons precipitation) and end in the fall (when conditions are favorable for the establishment of vegetation), if feasible. Minimize the amount and time that graded • Complete construction and erosion control activities in one areas are left exposed section of the site before beginning activity in another section. Utilize permeable and nutrient rich soils • Preserve any portion of the site with permeable soils to promote infiltration of stormwater runoff. • Leave areas of rich topsoil in place, or if excavated, utilize elsewhere on the site to amend areas with sparse or nutrient deficient topsoil. Reduce impact of construction access roads • Reduce the number and size (width/length) of construction access roads. • Locate construction access roads in areas where future roads and utility corridors will be placed (unless utilizing permeable pavement). Promote sheet flow and minimize • Avoid grading that results in steep, continuous slopes, concentrated runoff especially in areas contributing runoff to LID BMPs. LID BMP activation • LID BMPs shall not begin operation until all erosion -causing project improvements (including use of access roads that may contribute sediment) are completed and all exposed ground surfaces are stabilized by revegetation or landscaping in upland areas potentially contributing runoff to the BMP. Q 6. ADDITIONAL REQUIREMENTS 25 Packet Pg. 160 2.4.d Activities During Construction Many common construction -phase activities pose a risk to LID BMPs. The following techniques will help minimize these impacts. Techniques to be used for protection of LID BMPs include: Erosion Control Requirements Erosion Control Techniques Protect native topsoil during the • Where practicable, protect areas of rich topsoil. If excavation is construction phase, and reuse on site necessary, stockpile native soils that can be used on the site after construction. • Stockpile materials in areas designated for clearing and grading (such as parking areas and future impervious roadways) and away from infiltration and other stormwater facilities. • Cover small stockpiles with weed barrier material that sheds moisture yet allows air transmission. Large stockpiles may need to be seeded and/or mulched. • Do not relocate topsoil or other material to areas where they can cover critical root zones, suffocate vegetation, or erode into adjacent streams. Use effective revegetation methods • Use native plant species adapted to the local environment. • Plant during late fall, winter, or early spring months when vegetation is likely to establish quickly and survive. • Utilize proper seedbed preparation. Fertilize and mulch to protect germinating plants. Apply 1 inch of compost topped with 2 inches of mulch. • Protect areas designated for revegetation from soil compaction by restricting heavy equipment. • Provide proper soil amendments where necessary (refer to SWMMWW, Volume V, Chapter 5, BMP T5.13 Post - Construction Soil Quality and Depth). Amend soil toward the end of construction. Once established, protect from compaction and erosion. • During storage, plants should be protected by solar screens when possible to prevent overexposure and excessive drying. Perform preconstruction, routine, and • Conduct a preconstruction inspection to verify that adequate postconstruction inspections barriers have been placed around vegetation retention areas, infiltration facilities (as needed), and structural controls are implemented properly. • Conduct routine inspections to verify that structural controls are being maintained and effectively protecting LID BMPs throughout construction. • Conduct a final inspection to verify that revegetation areas are stabilized and that permanent LID BMPs are in place and functioning ro erl . 26 6. ADDITIONAL REQUIREMENTS Packet Pg. 161 2.4.d 6.1.3 BMP-Specific Construction Techniques This section outlines construction -phase BMP protection techniques specific to categories of LID BMPs (e.g., infiltration and dispersion) as well as specific LID BMPs (permeable pavement, bioretention areas/rain gardens, and vegetated roofs). The BMP protection techniques presented previously in Section 6.1.2 are applicable to the overall construction site to help protect LID BMPs. The techniques outlined in this section are based on the specific BMP functions, targeting typical construction activities that pose a risk to individual BMPs. Infiltration and Dispersion Facility Construction Techniques It is critical that appropriate methods are used to protect infiltration and dispersion BMPs from compaction and sediment loading during construction. For infiltration facilities in particular, the subgrade soils must be protected from clogging and over -compaction to maintain the soil permeability and ensure BMP performance. Techniques for protection of infiltration and dispersion BMPs during various stages of construction are summarized below. Construction Stage Techniques for Protecting Infiltration and Dispersion Facilities Prior to construction • The infiltration/dispersion area shall be clearly identified (e.g., using flagging or high visibility fencing) and protected prior to construction to prevent compaction of underlying soils by vehicle traffic. • Develop a soil and vegetation management plan showing areas to be protected and restoration methods for disturbed areas before land clearing sta rts. • The Construction SWPPP sheets must outline construction sequencing that will protect the infiltration/dispersion area during construction. • Construction SWPPP BMPs and protection techniques identified in the previous sections shall be implemented as applicable. In particular, be sure to stabilize upslope construction areas (e.g., using silt fences, berms, mulch, or other Construction SWPPP BMPs) and minimize overland flow distances. Excavation • Excavation of infiltration/dispersion areas shall be performed by machinery operating adjacent to the BMP. No heavy equipment with narrow tracks, narrow tires, or large lugged high pressure tires shall be allowed on the infiltration/dispersion area footprint. • Where feasible, excavate infiltration/dispersion areas to final grade only after all disturbed areas in the upgradient project drainage area have been permanently stabilized. (If infiltration areas must be excavated before permanent site stabilization, initial excavation must be conducted to no less than 6 inches of the final elevation of the facility floor.) • Excavation of infiltration areas shall not be allowed during wet or saturated conditions. • The use of draglines and trackhoes should be considered for constructing infiltration and dispersion areas. • The bottom (and sidewalls if feasible) of an infiltration facility excavation must be raked or scarified to a minimum depth of 3 inches after final excavation to restore infiltration rates. • Scarify soil along the dispersion flow path if disturbed during construction. 6. ADDITIONAL REQUIREMENTS 27 Packet Pg. 162 2.4.d Construction Stage Techniques for Protecting Infiltration and Dispersion Facilities Sediment control . Bioretention, rain garden, and permeable pavement BMPs shall not be used as sediment control facilities, and all drainage shall be directed away from the BMP location after initial rough grading. Direct construction site flow away from the infiltration/dispersion area using applicable Construction SWPPP BMPs (e.g., temporary diversion swales). Permeable Pavement There are many potential applications and site scenarios where permeable pavement can be applied. The following techniques highlight the most broadly applicable techniques to be used to protect permeable pavement BMPs during construction. Refer to the previous section for construction protection methods that are applicable to all infiltration BMPs, as well as Sections 6.1.1 and 6.1.2 for general site protection measures. In addition to those techniques, the following techniques apply specifically for protection of permeable pavement during construction: • Use procedural BMPs to plan construction. For example, phase construction to minimize compaction, sedimentation, or structural damage to the permeable pavement. • Use physical Construction SWPPP BMPs and/or grade the site to avoid sediment laden runoff from reaching permeable pavements. • Place protective surfaces (e.g., waterproof tarps and steel plates) over any permeable pavement areas used for construction staging. %% • Do not drive sediment -laden construction equipment on the base material or pavement. Do not allow sediment -laden runoff on permeable pavements or base materials. • Once the pavement is finished and set, cover the pavement surface with plastic and geotextile to protect from other construction activities. Close and protect the pavement area until the site is permanently stabilized. • Incorporate measures to protect road subgrade from over compaction and sedimentation if permeable pavement roads are used for construction access. o Cover the aggregate base or pavement surface with protective geotextile fabric and protect fabric with steel plates or gravel. Gravel should only be used to protect the fabric placed over aggregate base. o Once construction is complete and the site is permanently stabilized, remove protective geotextile, clean, and complete pavement installation. Refer to the detailed permeable pavement BMP information in SWMMWW Volume V, Chapter 5, as well as City of Edmonds Standard Details for general permeable pavement construction criteria. 28 6. ADDITIONAL REQUIREMENTS Packet Pg. 163 2.4.d Bioretention Areas and Rain Gardens As with permeable pavements, there are many potential applications and site scenarios where bioretention and rain garden BMPs can be applied. The following techniques highlight the most broadly applicable techniques to be used to protect bioretention and rain garden BMPs during construction. Refer to the beginning of this section for construction protection methods that are applicable to all infiltration BMPs, as well as Sections 6.1.1 and 6.1.2 for general site protection measures. In addition to those techniques, the following techniques apply specifically for protection of bioretention and rain garden BMPs during construction: • Excavation: o If machinery must operate in the bioretention area for excavation, use lightweight, low ground -contact pressure equipment and rip the base at completion to scarify soil to a minimum of 12 inches. • Protect bioretention soil mix from compaction during construction o Do not place bioretention soil mix if saturated or during wet periods. o Check for compaction prior to planting. If compaction occurs, aerate the bioretention soil and then proceed to plant. Refer to the detailed bioretention and rain garden BMP information in SWMMWW Volume V, Chapter 7, as well as City of Edmonds Standard Details for general bioretention and rain garden construction criteria. YV Vegetated Roofs The following additional techniques apply for protection of vegetated roof facilities during construction: • Because of their location and complexity, vegetated roofs typically require more planning and coordination effort relative to ground -level landscaping. For new construction, a critical path approach is highly recommended to establish the sequence of tasks for construction of the vegetated roof system. • During construction, it is vitally important that the waterproof membrane be protected once installed. The waterproofing should be tested prior to placement of the growth media and other subsequent vegetated roof materials. Refer to the detailed vegetated roof BMP information in SWMMWW Volume V, for general construction criteria. 6. ADDITIONAL REQUIREMENTS 29 Packet Pg. 164 2.4.d 6.2 OFF -SITE ANALYSES AND DOCUMENTATION All projects subject to Minimum Requirement No. 4 shall submit as part of their Stormwater Site Plan an off -site analysis that assesses the potential off -site impacts of stormwater discharges. The following sections detail the analysis and documentation requirements for Category 1 and Category 2 projects. 6.2.1 Category 1 Projects Category 1 projects shall submit a qualitative analysis of potential off -site impacts of stormwater discharges for each upstream drainage system entering a site, and each downstream drainage system leaving a site. The upstream analysis shall identify and describe points where water enters the site. Any upstream contributing areas shall be identified and mapped in the project Stormwater Site Plan submittal. The downstream analysis shall extend from the project site to the receiving water, or up to one -quarter mile, whichever is less. In many cases, runoff that leaves a project site will enter the City's MS4 within one -quarter mile. In these instances, the project must evaluate and document downstream conditions up to and including runoff entry into the City's MS4. In addition, the project proponent shall consult with the City to determine whether the MS4 has any existing or anticipated capacity issues downstream of the proposed project. The qualitative analysis shall identify where and how stormwater runoff will leave the proposed development site, and describe conditions downstream of the site including any existing or anticipated future problem areas (e.g., spot flooding, property damage, erosion issues, capacity -limited drainage systems, etc.). The qualitative analysis must be sufficient for the City to evaluate whether the project has adequately identified potential impacts and whether proposed mitigation measures are supported by the analysis. Some "rough" quantitative analyses, which can be based on non -surveyed field data, may be necessary as part of the qualitative analysis to adequately describe or document the extent of observed problem areas. Note that any off -site field visits should be conducted during winter months and after significant precipitation events to identify seasonal issues such as flooding, capacity constraints, or surface seeps or other indicators of near surface groundwater. A quantitative analysis may also be required for any project where the project proponent or the City determines that a more thorough analysis is necessary to evaluate the off -site impacts or the capacity of the conveyance system (e.g., where there is evidence of a risk to downstream systems such as erosion, flooding, property damage, habitat damage, water quality degradation, or other related impacts). A quantitative analysis may include calculations and/or modeling analyses of on -site and off -site water quality, erosion, slope stability, and other drainage -related impacts that may be caused or aggravated by a proposed project. 6.2.2 Category 2 Projects All Category 2 projects shall submit a qualitative analysis of potential off -site impacts of stormwater discharges that extend downstream from the site to the receiving water. (If the ultimate discharge point is to Puget Sound via a culvert owned by BNSF Railway, the analysis must be followed through the drainage system all the way to Puget Sound.) A quantitative analysis may also be required for any project deemed to need additional downstream information or where the project engineer or the City determines that a quantitative analysis is necessary to evaluate the off -site impacts or the capacity of the conveyance system (e.g., where there are known capacity issues or where there is evidence of a risk to downstream 30 6. ADDITIONAL REQUIREMENTS Packet Pg. 165 2.4.d systems such as erosion, flooding, property damage, habitat damage, water quality degradation, or other related impacts). The qualitative analysis must be sufficient for the City to evaluate whether the project has adequately identified potential impacts and whether proposed mitigation measures are supported by the analysis. Some "rough" quantitative analysis, which can be based on non -surveyed field data, may be required at this stage. A downstream analysis of the project for a minimum of one -quarter of a mile is required. The analysis must also extend upstream to a point beyond any backwater effects caused by the project. The analysis must include field -inspection of all existing stormwater drainage systems downstream from the project and a determination of whether the capacity of the drainage system(s) is adequate to handle the existing flows, flows generated by the proposed project, and any overflow. Adequacy will be evaluated based on conveyance capacity, flooding problems, erosion damage or potential, amount of freeboard in channel and pipes, and storage potential within the system. Note that site visits should be conducted during winter months and after significant precipitation events to identify undocumented surface seeps or other indicators of near surface groundwater. See the end of this section for specific topics to be discussed in the qualitative analysis. When deemed necessary by the project engineer or required by the City, a quantitative analysis shall include the qualitative analysis describe above, as well as quantitative calculations and/or modeling analyses of on -site and off -site water quality, erosion, slope stability, and other drainage -related impacts that may be caused or aggravated by a proposed project. Measures for preventing impacts and for not aggravating existing impacts shall also be identified. ("Aggravating existing impacts" means increasing the frequency of occurrence and/or severity of an impact.) The analysis shall document how temporary and permanent flow control and water quality control measures identified in the Stormwater Site Plan will mitigate the potential to create new problems or aggravate existing conditions. In many cases, design of flow control and water quality systems according to the procedures contained in this Addendum and the SWMMWW will be adequate demonstration of mitigation. However, upon review of this analysis and the severity of an existing problem, the City may require more detailed analysis and/or additional mitigation measures. In general, all existing and proposed off -site surface water conveyance systems shall be sized to convey flows without surcharging the City's storm system (or BNSF culverts under the railroad tracks, if applicable). Both the qualitative analysis and the quantitative analyses (when required) shall include descriptions and/or analyses of the following items. The descriptions shall identify existing or potential problem areas, and whether adequate mitigation can be identified (or whether more detailed quantitative analysis is necessary). References to other Stormwater Site Plan sections (e.g., facility sizing, conveyance, attachments and appendices, etc.) are encouraged to reduce plan redundancy, as long as all of the required Stormwater Site Plan issues are clearly presented: • Describe the drainage system between the site and the receiving surface waters. Provide information on pipe sizes, channel characteristics, and drainage structures. Describe emergency services located along the flow path (e.g., fire/police stations, hospitals). Describe environmentally sensitive areas, such as wetlands, etc. • Describe the upstream drainage tributary to the project. Describe any bypass drainage from the project which will not be controlled. • The bulk of the analysis shall focus on highlights of important considerations from the project overview and off -site analysis sections related to the drainage system and potential problems or concerns. Existing and potential impacts to be evaluated and mitigated shall include, but not be limited to: 6. ADDITIONAL REQUIREMENTS 31 Packet Pg. 166 2.4.d O Conveyance system capacity issues. o Flooding or bank overtopping. o Upland erosion impacts, including slope stability and landslide hazards. O Stream channel erosion (at the outfall location and to the downstream limit of analysis). O Violations of surface water quality standards as identified in a Basin Plan or a TMDL/Water Cleanup Plan (e.g., for Lake Ballinger). O For each existing or potential problem, document: the magnitude of damage caused by the problem, the general frequency and duration, current mitigation of the problem (if any), the likely or possible cause of the problem, and whether the project is likely to aggravate the problem or create a new one. • Determine whether the project is within any other critical areas or their buffers as defined in ECDC, and whether any additional requirements apply. • All areas pertinent to the analyses such as site boundaries, study area boundaries, streets and prominent features, downstream flow path, potential/existing problems, etc. shall be keyed to features shown on the project map(s). 6.3 DESIGN REQUIREMENTS FOR DETENTION VAULTS AND PIPES T This section includes design requirements and associated information for detention vaults and detention pipes. The focus of this section is on the use of detention vaults and pipes to meet Minimum Requirement No. 5. For other design applications (e.g., to meet Minimum Requirement No. 7), designers must refer to the SWMMWW. For Category 1 and 2 projects that must comply with Minimum Requirement No. 5, the final option that is available for roofs and other hard surfaces under List No. 1 and List No. 2 (per ECDC 18.30.060.D.5 [d] or [e]) is the use of detention vaults or detention pipes. When using detention vaults or pipes to comply with Minimum Requirement No. 5 using List No. 1 or List No. 2 in the City of Edmonds, the following requirements apply. Note that if the project is required to construct a flow control facility to comply with Minimum Requirement No. 7 (per ECDC 18.30.060.D.7), a detention vault is not required to be installed to meet Minimum Requirement No. 5. The City may waive the requirement to install a detention vault or pipe if the downstream analysis in Minimum Requirement No. 4, or available City data indicate that peak flow control is not beneficial. Note that this exemption is rare and most similar to the direct discharge exemption in SWMMWW; qualifin g for this exception will require unique site circumstances and may require additional information or calculations from the applicant to demonstrate lack of benefit. It shall not be applied to any site which discharges, direct or indirectly, to a stream, creek, wetland, or floodplain. 32 6. ADDITIONAL REQUIREMENTS Packet Pg. 167 2.4.d 6.3.1 Sizing & Design The City has created simplified sizing techniques for detention vaults and pipes for use in complying with Minimum Requirement No. 5. The sizing calculations and requirements presented below are designed to optimize detention facility functions relative to peak flow control as well as runoff "volume managed." Volume managed is a measure of the difference between facility inflow and outflow rates, and is evaluated using continuous simulation hydrologic modeling by comparing inflow and outflow over the entire continuous simulation. Volume managed represents an estimate of the amount of the storm flow that is attenuated (or removed, for facilities that utilize infiltration) by the flow control facility. To comply with Minimum Requirement No. 5, detention vaults or pipes must be installed for any site impervious surfaces totaling greater than or equal to 1,000 square feet that are not managed by other On - Site Stormwater Management BMPs. This includes areas from multiple types of surfaces listed under the list options in Minimum Requirement No. 5. For example, if unmanaged flows from roofs plus driveway areas exceed 1,000 square feet and runoff from both surfaces can be routed to a single vault, a vault shall be installed. In addition, projects may elect to route "managed" flows to the vault if desired (e.g., where runoff from an installed On -Site Stormwater Management BMPs cannot be easily separated from runoff drainage to the vault.) In this scenario, no upsizing of the vault is required for the "managed" areas. Only the unmanaged surfaces need to be included in the sizing calculations below. The City of Edmonds has developed standards specifically for vaults and pipes used to meet Minimum Requirement No. 5 only. See City standard detail SD-651 for detention tank requirements specific to minimum Requirement #5; this detail shall be completed with design information and included with any elan set nr000sina detention under Minimum Reauirement #5. For compliance with Minimum Requirement No. 7, SWMMWW Volume V, Chapter 12 requirements apply. For vaults efTipe-s-with contributing areas greater than or equal to 1,000 square feet the following sizing requirements apply: • Orifice size for- vaults and pi-pes fyms+shall be 0.5 inches • Vault interior bottom area = 2 percent of contributing surface area • Vault minimum active storage depth = 3.0 feet �as�ssrsassa�- -- • ��• 6. ADDITIONAL REQUIREMENTS 33 Packet Pg. 168 2.4.d 6.4 UNDERGROUND INJECTION CONTROLS With each update to the SWMMWW, the Department of Ecology continues to emphasize the importance of maximizing the use of infiltration for stormwater runoff control. Given the heavy emphasis on infiltration in the SWMMWW, and thus ECDC 18.30 and this Addendum, it is important to be aware of related requirements for Underground Injection Controls (UICs). In certain situations, BMPs that rely on infiltration are classified as UICs and may be regulated by Ecology under the UIC Program (Washington Administrative Code [WAC] 173 218). For more information on UICs, see the 2006 Eeelegy deetiment titled dui a-mee fe UIC Wells��ge Steat .SWMMWW Volume I, Chapter 4 (UIC Program). *IV 34 6. ADDITIONAL REQUIREMENTS Packet Pg. 169 2.4.d 7 SUBMITTAL REQUIREMENTS Stormwater Site Plans are required for all projects subject to Minimum Requirement No. 1 — Preparation of Stormwater Site Plans (as well as for preparation of a Construction SWPPP, in accordance with Minimum Requirement No. 2), as outlined in Chapter 3 and ECDC 18.30.060.C. This chapter summarizes the requirements for submittals of stormwater plans, reports, and other documents for review by the City of Edmonds. As noted in Section 5.1, Stormwater Site Plans shall be prepared in accordance with Chapter 3 of Volume 1 of the SWMMWW. However, the City of Edmonds has developed checklists to facilitate compliance with Minimum Requirement No. 1 (and thus project submittal and review). This Addendum includes a summary of core submittal requirements for Category 1 and Category 2 projects as Checklists 1 and 2 in Appendix C. 7.1 CATEGORY 1 STORMWATER SITE PLANS Stormwater Site Plans for Category 1 projects must address Minimum Requirements No. 1 through No. 5 Detailed descriptions of submittal requirements are provided in Appendix C, Checklists 1 through 3. A schematic showing the components of a typical Category 1 project submittal is presented in Figure 7.1. Typical Category 1 Stormwater Site Plan Components Site Development Drawings and Reports and Construction SWPPP Drawings Documentation (i.e., construction drawings) Stormwater Site Plan Report, Supporting Documents, and Calculations Soils Report Construction SWPPP Narrative Establishment of Maintenance Covenant Appendices Figure 7.1. Typical Category 1 Stormwater Site Plan Components. 7.2 CATEGORY 2 STORMWATER SITE PLANS Stormwater Site Plans for Category 2 projects include the full submittal package meeting all minimum requirements. The Category 2 Stormwater Site Plan submittal package includes the following 7. SUBMITTAL REQUIREMENTS 35 Packet Pg. 170 2.4.d components: Stormwater Site Plan Report, Site Development Drawings, Soils Report, Construction SWPPP, Operations and Maintenance Manual, Maintenance Covenant, and any plan appendices. A schematic showing the components of a typical Category 2 Stormwater Site Plan submittal package is presented in Figure 7.2. The Construction SWPPP consists of two parts: a narrative report and drawings, which should be included in the plan set with the other Site Development Drawings. Detailed descriptions of submittal requirements are provided in Appendix C, Checklist 2. Typical Category 2 Stormwater Site Plan Components Site Development Drawings Reports and (i.e., construction drawings) Documentation Stormwater Site Plan Report, General Drawings Supporting Documents, and Calculations Construction SWPPP Drawings Soils Report Grading/Earthwork Drawings Construction SWPPP Narrative Plan/Profile Drawings Operation and Maintenance Manual Detail Drawings Establishment of Maintenance Covenant Appendices Figure 7.2. Typical Category 2 Stormwater Site Plan Components. 36 7. SUBMITTAL REQUIREMENTS Packet Pg. 171 2.4.d Appendix A — On -Site Stormwater Management BMP Infeasibility Criteria Packet Pg. 172 2.4.d Q Packet Pg. 173 j� �n�oNE 201,?OCTOBER 2021 EDMONDS STORMWATER ADDENDUM 2.4.d Appendix B — Methods for Determining Design Infiltration Rates Packet Pg. 174 2.4.d Q Packet Pg. 175 j� �n�oNE 201,?OCTOBER 2021 EDMONDS STORMWATER ADDENDUM 2.4.d Appendix C — Checklists for Various Project Submittal, Review, and Field Procedure Elements Packet Pg. 176 2.4.d Q Packet Pg. 177 2.4.d Appendix D — Design Checklists for the Main On -Site Stormwater Management BM Ps j Packet Pg. 178 2.4.d a Packet Pg. 179 2022 ECDC 18.30 and Stormwater Addendum Summary of Changes 2.4.e # Document Section Direction Summary of Old requirement Summary of New requirement Estimated Impact (Old/new) From Minimal as most revisions were re -organization of existing elements; see Ecology 1 ECDC 18.30 Entirety Ecology Aligned with 2014 SWMMWW Aligned with 2019 SWMMWW Executive Summary and Crosswalk documents for more information. 2 ECDC 18.30 18.30.010 EcologyAligned with previous NPDES permit Appendix 1 g p p pp Aligned with new NPDES permit Appendix 1 g p pp Minimal; City code did not include a couple of the definitions listed in Appendix A but revised/new definitions generally consistent with previous definitions. "Road -related project" definition vague on application "Road -related project" definition revised to clarify that None; added for clarity only. Revised definition is consistent with City staff 3 ECDC 18.30 18.30.010 City Staff to frontage improvements as part of development frontage improvements as part of development project interpretation which was confirmed by Ecology staff. project are not considered road -related projects "Site" definition which does not address relationship "Site" definition updated to clarify that drainage None; added for clarity only. Revised definition is consistent with previous City staff 4 ECDC 18.30 18.30.010 City Staff with separate definition for "project site" requirements are assessed against the "project site", not . interpretation. this definition. 5 ECDC 18.30 18.30.010 Ecology Old Example TDA Delineations figure Updated Example TDA Delineations figure None; revised for clarity only. Makes new standard effective to (1) new projects after Jan. 1, 2022, (2) projects under a previous/older version of drainage code but not under construction yet, and (3) projects approved under the current drainage code which have not started construction 6 ECDC 18.30 18.30.030 Ecology Old dates of applicability for previous code. Updated dates of new code applicability. by 2027. These dates align with specific requirements per the revised NPDES permit; except that new code applies starting January 1, 2022 instead of last acceptable date of July 1, 2022. This is essentially the states way of managing the vesting of drainage requirements. 7 ECDC 18.30 18.30.040 Ecology ,,i Older language referring to "impervious" simplified, Newer language referring to "hard" surfaces, , None; revisions for clarity and constancy only. and rearranged to better match SWMMWW format 18.30.040. "Underground utility project" exemption does not "Underground utility project" exemption clarifies that None; added for clarity only. Revised definition is consistent with previous City staff 8 ECDC 18.30 B.1 City Staff define underground utility project. utilities as part of development do not qualify for this interpretation. partial exemption. New connections for areas over 2,000 to be handled like Closes loop hole which could impact City system, but may limit resident options for 18.30.060. New connections for existing surfaces were addressed anew project, and all surfaces mitigated unless home improvement (non -development) projects. This limits impacts to City system and 9 ECDC 18.30 City Staff case -by -case and allowed applicant to potentially aligns with the intent of SWMMWW better (which seeks to return flows to historic, C.3 connect without mitigation if determine acceptable. applicant can demonstrate previous drainage was forested, conditions), but homeowners seeking to improve their home (without similar impact on City system. development/expansion), may be impacted by this additional burden as well. 18.30.060. Treatment trade/equivalent area text scattered through Explicit language permitting the use of equivalent areas None; revised language form Ecology is consistent with past staff interpretations and 10 ECDC 18.30 C.4 Ecology out document. for stormwater mitigation. the use equivalent areas was already being permitted within Edmonds. Retrofit requirement requires 25% of existing Additional protection for Perrinville Creek but potential additional cost to home owners 11 ECDC 18.30 18.30.060. City Staff unmanaged surfaces to remain on a project site, to be Specific to Perrinville Basin, the value increases form and developers. This provisions not only seeks to limit further impacts from D.S.b.i mitigated per minimum requirement #5 ( LID 25% to 50%. development to the creek, it actually seeks to partially address historic impacts which requirement) for all areas. have already been impressed upon the creek. 18.30.060. Retrofit requirement a bit vague on impact to other Added clarifying text that retrofit is a stand alone None; added for clarity only. Revised definition is consistent with City staff 12 ECDC 18.30 D.S.b.i City Staff requirements. requirement for MR #5 which does not impact other interpretation. thresholds or application of minimum requirements. Projects on Edmonds Way will comply with same drainage standard as rest of City. This 13 ECDC 18.30 18.30.060. City Staff Reduced BMP list and flow standard for Edmonds Way No exception or reduction for Edmonds Way system is known to overflow to Edmonds Marsh which means it no longer has capacity D.S.b.iv basin as direct discharge basin. for further under -mitigated development and contributes to a non -man-made drainage course; both are factors making this basin not eligible to be a direct discharge basin. Page 1 of 3 Versi packet Pg. 180 2022 ECDC 18.30 and Stormwater Addendum Summary of Changes 2.4.e # Document Section Direction Summary of Old requirement Summary of New requirement Estimated Impact (Old/new) From New section addressing rare case where projects have expansions under thresholds, but would impact and This is a rare circumstance, and designers would simply route such minor addition areas 14 ECDC 18.30 18.30.060. City Staff N/A - New section existing infiltration systems with surface overflows. Such to a separate drywell/infiltration system in most cases so while this revisions closes a D.S.b.vi cases shall expand the BMP accordingly to not have new loop hole, the actually impacts to project is anticipated to be minimal. impacts. 18.30.060. Direct discharge permitted some exceptions from Explicitly requires the application of the amended soils None; added for clarity only. Revised definition is consistent with previous City staff 14 ECDC 18.30 Ecology D.S.c.i certain BMPs, but vague. BMP even when meeting performance criteria. interpretation. 18.30.060. Full dispersion and full infiltration listed in same bullet in Full infiltration separated as its own bullet, just under None, revise for clarity only. Because all other BMPs are listed individually, full 15 ECDC 18.30 City Staff D.S.d & e list full dispersion. infiltration is often overlooked by designers. Reduces use of perforated pipe connection on SFRs and gains more detention. Perforated pipe connections are a last ditch effort to get infiltration on sites which otherwise have been determined infeasible for full infiltration; because of this staff believe they achieve very little been fit from a stormwater perspective. Often designers 18.30.060. Perforated pipe connection listed as higher priority than Detention tanks listed as higher priority than perforated want to put the perforated pipe connection in risky places to avoid detention. It has 16 ECDC 18.30 City Staff D.S.d & e detention tanks in all LID BMP Lists pipe connections in all LID BMP Lists also been leveraged against a partial exemption for detention for infeasible surfaces collection to avoid a driveway BMP all together. Because Edmonds has the unique code which adds detention tanks to the bottom of the Ecology required BMP list, the City drainage system would be better protected by requiring a detention tanks before perforate pipe connections. Hard surfaces BMP list does not include full infiltration Full infiltration added as equal to permeable pavements None, revise for clarity only. Staff have permitted full infiltration in other BMPs in -lieu 17 ECDC 18.30 18.30.060. City Staff option other than permeable pavements. Permeable and raingardens/bioretention separate as its own bullet of permeable pavements. Because all other BMPs are listed individually, D.S.d & e pavements listed as second priority, and with below full infiltration/permeable pavements. raingardens/bioretention was often overlooked. raingardens/bioretention. 18.30.060. Detention tank language included in exclusions each Detention additional exclusions moved Section 6.3 of None, revise for clarity only. Exception extra/repeated text explanation as was more 18 ECDC 18.30 City Staff D.S.d & e time detention tank was listed. the Edmonds Addendum instead. appropriate in addendum text than in these bulleted lists. "Overflows" section added to clarify City overflow expectations for BMPs meeting MR #5 only. Piped 18.30.060. overflow required unless project infiltrates full 100-year None; added for clarity only. Revised definition is consistent with City staff 19 ECDC 18.30 City Staff None; new section. D.S.f storm. Re -iterates that surface route still needs to be interpretation. controlled if permitted. Provide very rough guidance on extension length expectations. Language regarding untreated discharges to 18.30.060. Language regarding untreated discharges to 20 ECDC 18.30 Ecology groundwater included updated to match latest version None, revision for clarity and consistency only. D.6 groundwater included old references. and references. Flow control exemption text for direct discharges to Puget Sound did not include reference to additional 18.30.060. Additional requirements necessary to qualify for a direct None; added for clarity only. Revised section is consistent with previous City staff 21 ECDC 18.30 City Staff requirements necessary to demonstrate compliance D.7 discharge exemption is now referenced. interpretation. with the associated minimum requirement for the exemption. New section for elevated flow control in Perrinville Creek basin. Language is the same as King County's Better protection of Perrinville Creek; which is significantly impacted by historic upland 22 ECDC 18.30 18.30.060. City Staff Standard flow control for all areas of City Level 3 flow control standard which requires matching development. Larger developments (> 10,000 SF) will have to install larger retention D 7 the 100-year peak in addition to standard flow control systems (increased cost). standards. Page 2 of 3 Versi packet Pg. 181 2022 ECDC 18.30 and Stormwater Addendum Summary of Changes 2.4.e # Document Section Direction Summary of Old requirement Summary of New requirement Estimated Impact (Old/new) From References new Ecology section for UIC. New section Limited impact; UICs under this program are under Ecology authority for approval not provides additional guidance and generally states that City. City notifies applicant of need to file UIC notice with Ecology and continues 23 Addendum Section 2.4 Ecology UIC referenced old code section. discharges to UICs must meet the provisions of drainage review per typical application of SWMMWW provisions (namely water quality SWMMWW. treatment). No language supporting the existing internal policy of None; added for clarity only. Revised section is consistent with previous City staff 24 Addendum Section 2.6 City Staff Language added to prohibit the use of CMP pipes. prohibiting the use of CMP pipes. interpretation. Closes loop hole which could impact City system, but may limit resident options for home improvement projects. Previously, this section allowed new connections to the Update to match revisions to 18.30.060.C.3; minimum City system without mitigation for existing surfaces. Section revised to require typical requirements apply to new connection of non- mitigation for all new connections draining more than 2000 SF of hard surfaces, unless 25 Addendum Section City Staff Reflected old 18.30.060.C.3 language development projects over 2,000 SF impervious unless applicant can demonstrate that the City system will not be impacted in any way. This 3.1.2 applicant can demonstrate previous drainage was limits impacts to City system and aligns with the intent of SWMMWW better (which similar impact on City system. seeks to return flows to historic, forested, conditions), but homeowners seeking to improve their home (without development/expansion), may be impacted by this additional burden as well. Language update to include missing departures formNone; Section List of change form SWMWW missing a couple existing added for clarity only. Revised section is consistent with previous City staff 26 Addendum City Staff SWMMWW; none of the referenced code is new, the 3.1.3 differences. interpretation. items were just added to the list for clarity. Projects on Edmonds Way will comply with same drainage standard as rest of City. This Edmonds Way explicitly stated not to be consider a system is known to overflow to Edmonds Marsh which means it no longer has capacity 27 Addendum Section 4.1 City Staff Edmonds Way included as a direct discharge basin direct discharge basin due to overflow to Edmonds for further under -mitigated development and contributes to a non -man-made drainage Marsh. course; both are factors making this basin not eligible to be a direct discharge basin. None; added for clarity only. Revised section is consistent with previous City staff 28 Addendum Section 5.3 City Staff Policy to prohibit CMP not actually in code. Updated language to reflect prohibition of CMP interpretation and extremely rare. Projects on Edmonds Way will comply with same drainage standard as rest of City. This No exception or reduction for Edmonds Way; update system is known to overflow to Edmonds Marsh which means it no longer has capacity 29 Addendum Section 5.5 City Staff Reduced BMP list and flow standard for Edmonds Way. consistent with update to 18.30.060.D.5.b.iv, above. for further under -mitigated development and contributes to a non -man-made drainage course; both are factors making this basin not eligible to be a direct discharge basin. Vague requirements for sites not draining to MS4 but Revised language to make it more clear that pumping to None; added for clarity only. Revised section is consistent with previous City staff 30 Addendum Section 5.5 City Staff pumped to MS4 in post -project conditions. MS4 requires application of all provisions in ECDC 18.30 interpretation and extremely rare. BMP sizing direction tucked within each checklist or Paragraph 7 added to clarify simplified sizing per None; added for clarity only. Revised section is consistent with previous City staff 31 Addendum Section 5.5 City Staff BMP description but never referenced in MR #5 section SWMMWW is allowable but requires piped overflow. interpretation. Detention vault requirements for MR #5 included vague Additional language added to the extra City requirement None; added for clarity only. Revised section is consistent with previous City staff 32 Addendum Section 6.3 City Staff line about City allowing exception to this requirement for detention tank under MR #5 to clarify application of for certain cases. their exception. interpretation. Section Detention tank text updated to reference new standard None; added for clarity only. Revised section and detail are consistent with previous 33 Addendum 6.3.1 City Staff Detention Tank specification provide via text detail for detention tanks/ City staff direction. Page 3 of 3 Versi packet Pg. 182 2.4.f Ecology Executive Summary of the 2019 Revisions & Edmonds Response The Stormwater Management Manual for Western Washington (SWMMWW) provides guidance on the measures necessary to control the quantity and quality of stormwater. Local municipalities use this manual to set stormwater requirements for new development and redevelopment projects. Land developers and development engineers use this manual to design permanent stormwater control plans, create construction stormwater pollution prevention plans, and determine stormwater infrastructure. Businesses use this manual to help design their stormwater pollution prevention plans. The greatest use of the SWMMWW has been through National Pollutant Discharge Elimination System (NPDES) stormwater permits. The Municipal Stormwater General Permits for western Washington incorporate and reference the SWMMWW. The Industrial Stormwater General Permit, Construction Stormwater General Permit, Boatyard General Permit, and the Sand and Gravel General Permit reference the SWMMWW. Since 2005, Ecology has reissued or issued for the first time all of these NPDES stormwater permits. The 2019 revisions to the SWMMWW will continue to help permittees comply with these permits. This document is a modified version of the Executive Summary of the 2019 Revisions as provided by the Department of Ecology. Black text represent text from the original Ecology document, while red text indicates text added by City of Edmonds staff. City - added text outlines how the City documents were updated (if needed) to reflect the corresponding Ecology revision. Prepared By: Zachary Richardson, City of Edmonds Stormwater Engineer Updated: June 22, 2021 Types of Revisions Usability Enhancements The focus of the 2019 update was to enhance the usability, which will result in improved implementation of the stormwater permits that rely on this guidance. Enhancements include: • Fully embracing the online user (maintain the interactive online format) • Consolidating repetitive information • Revising text for clarity • Reordering sections for a better flow of concepts References in ECDC checked against SWMMWW crosswalk and updated as needed. Several sections updated for clarity per City staff direction as well; see separate Edmonds Summary of Change document for additional information. Packet Pg. 183 2.4.f Significant Changes Ecology also identified the following changes that must be made in order to continue to provide the best guidance available: Continuous Simulation Modeling: Text throughout the SWMMWW has been updated to require continuous simulation models that include: o The ability to directly model BMPs that may be used in LID applications, such as bioretention, permeable pavement, and green roofs. 0 15-minute time steps. o Incorporation of the van Genuchten algorithm to model bioretention. Changes to this section were entirely within referenced sections of SWMMWW; no change within ECDC is needed. 2. Replaced Hard Surfaces Redevelopment Threshold: The Minimum Requirement Thresholds for non -road related commercial or industrial redevelopment projects have been updated to require the project proponent to compare the value of the proposed improvements to the value of the Project Site (the limits of disturbance) improvements, rather than the Site (the entire parcel) improvements. The re -development provisions associated with project valuation were previously removed from ECDC 18.30; no changes within ECDC needed. 3. Equivalent Areas: The Redevelopment Project Thresholds have been updated to allow a project proponent to provide Stormwater Management BMPs for an equivalent area. The equivalent area may be on -site, or off -site if the area drains to the same receiving water and the guidance for in -basin transfers is followed. ECDC 18.30.060.C.4 added to include language from Appendix 1. The new language is consistent with past staff interpretation and is not a new impact in practice. 4. Minimum Requirement 2: The 13 Elements in 1-3.4.2 MR2: Construction Stormwater Pollution Prevention Plan (SWPPP) have been updated to incorporate changes that were made to the 2015-2020 Construction Stormwater General Permit. Changes to this section were entirely within referenced sections of SWMMWW; no change within ECDC is needed. 5. Minimum Requirement 5: 1-3.4.5 MR5: On -Site Stormwater Management has been updated to require BMP T5.13: Post -Construction Soil Quality and Depth when choosing to use the LID Performance Standard to meet Minimum Requirement 5 for Minimum Requirement 1-5 projects. Packet Pg. 184 2.4.f ECDC 18.30.060.D.5.c.i added to require BMP T5.13 when meeting performance criteria. The new language is consistent with past staff interpretation and is not a new impact in practice. 6. Minimum Requirement 7: 1-3.4.7 MR7: Flow Control has been updated to ensure that a TDA discharging to a marine waterbody meets all exemption requirements before it can be determined to be Flow Control exempt. Changes to this section were already incorporated into City code in ECDC 18.30.060.D.5.b.iv; no change within ECDC is needed. 7. Concrete Washout BMPs: BMP C151: Concrete Handling and BMP C154: Concrete Washout Area have been updated to clarify that auxiliary concrete truck components and small concrete handling equipment may be washed into formed areas awaiting concrete pour, while concrete truck drums must be washed either off -site or into a concrete washout area. Changes to this section were entirely within referenced sections of SWMMWW; no change within ECDC is needed. 8. Source Control BMPs: Volume IV (Source Control BMP Library) has been updated with Source Control BMPs for activities not listed in previous versions of the manual. The new activities with Source Control BMPs are: o S434 BMPs for Dock Washing o S441 BMPs for Potable Water Line Flushina, Water Tank Maintenance, and Hydrant Testing o S435 BMPs for Pesticides and an Integrated Pest Management Program o S444 BMPs for the Storage of Dry Pesticides and Fertilizers o S449 BMPs for Nurseries and Greenhouses o S450 BMPs for Irrigation o S445 BMPs for Temporary Fruit Storage o S439 BMPs for In -Water and Over -Water Fueling o S436 BMPs for Color Events o S438 BMPs for Construction Demolition o S440 BMPs for Pet Waste o S442 BMPs for Labeling Storm Drain Inlets On Your Property o S443 BMPs for Fertilizer Application o S446 BMPs for Well, Utility, Directional and Geotechnical Drillini o S447 BMPs for Roof Vents o S451 BMPs for Buildina. Repair. Remodelina. Paintina, and Cnnstructinn o S452 BMPs for Goose Waste Changes to this section were entirely within referenced sections of SWMMWW; no change within ECDC is needed except to update references as needed. Packet Pg. 185 2.4.f 9. Wetlands Guidance: Appendix I-C: Wetland Protection Guidelines and I- 3.4.8 MR8: Wetlands Protection have been updated to require monitoring and modeling of high value wetlands, if the project proponent has legal access to them. The 2014 wetland guidance is retained, but refined, for modeling requirements for lower value wetlands (and high value wetlands that the project proponent does not have legal access to). Changes to this section were entirely within referenced sections of SWMMWW; no change within ECDC is needed. Other Updates Other updates include: Incorporation of UIC Program guidance. See 1-4 UIC Program. Edmonds Addendum Section 2.4 updated with revised reference to new UIC section. Expanded guidance for regional facilities. See Appendix I-D: Regional Facilities Changes to this section were entirely within referenced sections of SWMMWW; no change within ECDC is needed. Guidance for stormwater control transfer programs. See Appendix I-E: Stormwater Control Transfer Program. Changes to this section were entirely within referenced sections of SWMMWW; no change within ECDC is needed. Packet Pg. 186 5/11/2021 Crosswalk: 2014 - 2019 SWMMWW Dept. of 2.4.g Crosswalk: 2014 - 2019 SWMMWW Ecology has provided the crosswalk below to help you identify where content has been moved and/or renamed -2 between the 2014 and 2019 manuals. Note that during the 2019 update some sections were merged together cu a and/or edited for clarity. Therefore, you may not find the exact language from the 2014 manual in the linked 0 sections of the 2019 manual indicated below. The links below will lead you to where the updated content is co contained in the 2019 manual, providing updated guidance on the topic from the 2014 manual. v Crosswalk: 2014 - 2019 SWMMWW Location of Content within the 2014 SWMMWW Location of Content within the 2019 SWMMWW Executive Summary Executive Summary of the 2019 Revisions Volume I Content Volume I Acknowledgments Acknowledgments 1-1 - Introduction (no content in this section) 1-1.1 - Objective 1-1.1 About This Manual 1-1.2 - Applicability to Western Washington 1-1.2 Applicability to Western Washington 1-1.3 - Organization of this Manual 1-1.1 About This Manual 1-1.4 - How to Use this Manual 1-1.1 About This Manual 1-1.5 - Development of Best Management Practices 1-1.5 Types of Best Management Practices for Stormwater Management .(BMPs) for Stormwater Management 1-1.6 - Relationship of this Manual to Federal, State, 1-2 Relationship of This Manual to Permits, and Local Regulatory Requirements Requirements, and Programs 1-1.7 - Effects of Urbanization 1-1.3 Effects of Urbanization 1-2 - Minimum Requirements for New Development 1-3.1 Introduction to the Minimum and Redevelopment Requirements 1-2.1 - Relationship to Municipal Stormwater 1-2.4 Phase I and Western Washington Phase Permits II Municipal Stormwater Permits 1-2.2 - Exemptions 1-3.2 Exemptions 1-2.3 - Definitions Related to Minimum Requirements Glossary_ I https://fortress.wa.gov/ecy/ershare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/Crosswalk2014-2019.htm%3FTo,P Packet Pg. 187 5/11/2021 Crosswalk: 2014 - 2019 SWMMWW Dept. of 2.4.g Location of Content within the 2014 SWMMWW Location of Content within the 20 19 SWMMWW 1-2.4 - Applicability of the Minimum Requirements 1-3.3 Applicability of the Minimum Requirements 1-2.5 - Minimum Requirements 1-3.1 Introduction to the Minimum Requirements I-2.5.1 -Minimum Requirement #1: Preparation 1-3.4.1 MR1: Preparation of Stormwater Site M of Stormwater Site Plans Plans 00 U 1-2.5.2 - Minimum Requirement #2: Construction 1-3.4.2 MR2: Construction Stormwater w Stormwater Pollution Prevention (SWPP) Pollution Prevention Plan (SWPPP). 0 1-2.5.3 - Minimum Requirement #3: Source Control of Pollution 1-3.4.3 MR3: Source Control of Pollution E a� a� I-2.5.4 -Minimum Requirement #4: Preservation 1-3.4.4 MR4: Preservation of Natural Drainage CU of Natural Drainage Systems and Outfalls Systems and Outfalls r 1-2.5.5 - Minimum Requirement #5: On -site 1-3.4.5 MR5: On -Site Stormwater E Stormwater Management Management �° 4- 1-2.5.6 - Minimum Requirement #6: Runoff r_ Treatment 1-3.4.6 MR6: Runoff Treatment ° w c 1-2.5.7 - Minimum Requirement #7: Flow Control 1-3.4.7 MR7: Flow Control L a 1-2.5.8 - Minimum Requirement #8: Wetlands Protection 1-3.4.8 MR8: Wetlands Protection 1-2.5.9 - Minimum Requirement #9: Operation and Maintenance 1-3.4.9 MR9: Operation and Maintenance o N 1-2.6 - Optional Guidance 1-3.5 Additional Protective Measures o .(Optional) N i I-2.7 -Adjustments 1-3.6.1 Adjustments to the MRs 3 I-2.8 -Exceptions/Variances 1-3.6.2 Exceptions/Variances to the MRs i 1-3 - Preparation of Stormwater Site Plans III-3.1 Introduction to Stormwater Site Plans aD 1-3.1 - Stormwater Site Plans: Step -by -Step III-3.2 Preparing a Stormwater Site Plan r 111-3.3 Changes to a Previously Approved r Q w Stormwater Site Plan 1-3.2 - Plans Required After Stormwater Site Plan E Approval and a III-3.4 Final Corrected Plan Submittal I https://fortress.wa.gov/ecy/ershare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/Crosswalk2014-2019.htm%3FTo,P Packet Pg. 188 5/11/2021 Crosswalk: 2014 - 2019 SWMMWW Dept. of 2.4.g Location of Content within the 2014 SWMMWW Location of Content within the 20 19 SWMMWW 1-4 - BMP and Facility Selection Process for Permanent (no content in this section) Stormwater Control Plans a� r 1-4.1 - Purpose 1-2.2 AKART 0 1-4.2 - BMP and Facility Selection Process III-1 Choosing Your BMPs M 00 U Volume I References References w aD Appendix I -A: Guidance for Altering the Minimum o Requirements through Basin Planning Appendix I-B: Basin Plans U c m Appendix I-B: Rainfall Amounts and Statistics Appendix III-C: Rainfall Amounts and Statistics Appendix I-C: Basic Treatment Receiving Waters Appendix III -A: Basic Treatment Receiving Waters r Appendix I-D: Guidelines for Wetlands when Managing Stormwater Appendix I-C: Wetland Protection Guidelines E 0 Appendix I-E: Flow Control -Exempt Surface Waters Appendix IA Flow Control Exempt Receiving o Waters o Appendix I-F: Basins with 40% or more Total I-3.4.7 MR7: Flow Control M Impervious Area as of 1985 y Appendix I-G: Glossary and Notations Glossary_ a Volume II Content Volume II Acknowledgments Acknowledgments r 0 N Acronyms Glossary_ 0 II-1 - Introduction to Construction Stormwater Pollution `"i Prevention (no content in this section) 3 II-1.1 - Purpose of this Volume Executive Summary of Volume II U� c9 11-1.2 - Content, Organization, and Use of this Volume I-1.1 About This Manual E t II-1.3 -Thirteen Elements of Construction I-3.4.2 MR2: Construction Stormwater Q Stormwater Pollution Prevention Pollution Prevention Plan (SWPPP). E II-1.4 -Erosion and Sedimentation Impacts 11-1.3 Soil Erosion and Sedimentation Impacts https://fortress.wa.gov/ecy/ershare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/Crosswalk2014-2019.htm%3FTo,P Packet Pg. 189 5/11/2021 Crosswalk: 2014 - 2019 SWMMWW Dept. of 2.4.g Location of Content within the 2014 SWMMWW Location of Content within the 20 19 SWMMWW II-1.1 Soil Erosion II-1.5 - Erosion and Sedimentation Processes and a II-1.2 Sedimentation 0 M II-1.6 - Factors Influencing Erosion Potential II-1.1 Soil Erosion 00 T" 0 II-2 - Regulatory Requirements 1-2 Relationship of This Manual to Permits, w Requirements, and Programs 11-2.1 - The Construction Stormwater General L) Permit 1-2.7 Construction Stormwater General Permit E a� II-2.2 -Construction Stormwater Pollution II-2.2 When is a Construction SWPPP Prevention Plans Required? L d II-2.3 -Water Quality Standards 1-2.10 Water Quality Standards E 11-2.4 - Endangered Species Act 1-2.8 Endangered Species Act ° U) 4- 0 II-2.5 - Other Applicable Regulations and Permits I-2.15 Other Requirements c .W II-3 - Planning II-2 Construction Stormwater Pollution Prevention Plans (Construction SWPPPs) L 11-3.1 - General Guidelines II-2 Construction Stormwater Pollution a Prevention Plans (Construction SWPPPs) 11-3.2 - Construction SWPPP Requirements II-2.4 Preparing Construction SWPPPs � 11-3.3 - Step -by -Step Procedure II-2.4 Preparing Construction SWPPPs 0 II-4 -Best Management Practices Standards and II-3.1 A Summary of Construction Stormwater cm .� Specifications BMPs o N I 11-4.1 - Source Control BMPs II-3.1 A Summary of Construction Stormwater BMPs 0 N BMP C101: Preserving Natural Vegetation BMP C101: Preserving Natural Vegetation ° U I BMP C102: Buffer Zones BMP C102: Buffer Zones a� BMP C103: High Visibility Fence BMP C103: High -Visibility Fence BMP C105: Stabilized Construction a Entrance/Exit BMP C105: Stabilized Construction Access E BMP C106: Wheel Wash BMP C106: Wheel Wash a https://fortress.wa.gov/ecy/ershare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/Crosswalk2014-2019.htm%3FTOCP Packet Pg. 190 5/11/2021 Crosswalk: 2014 - 2019 SWMMWW Dept. of 2.4.g Location of Content within the 2014 SWMMWW Location of Content within the 20 19 SWMMWW BMP C107: Construction Road/Parking Area BMP C107: Construction Road / Parking Area Stabilization Stabilization r BMP C120: Temporary and Permanent Seeding BMP C120: Temporary and Permanent Seeding o BMP C121: Mulching BMP C121: Mulching00 M U BMP C122: Nets and Blankets BMP C122: Nets and Blankets w a BMP C123: Plastic Covering BMP C123: Plastic Covering o U BMP C124: Sodding BMP C124: Sodding E a� BMP C125: Topsoiing/Composting BMP C125: Topsoiling / Composting a� CU BMP C126: Polyacrylamide (PAM) for Soil BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection Erosion Protection E L BMP C130: Surface Roughening BMP C130: Surface Roughening 0 y 0 BMP C131: Gradient Terraces BMP C131: Gradient Terraces .2 w BMP C140: Dust Control BMP C140: Dust Control L BMP C150: Materials on Hand BMP C150: Materials on Hand a BMP C151: Concrete Handling BMP C151: Concrete Handling BMP C152: Sawcutting and Surfacing Pollution BMP C152: Sawcutting and Surfacing Prevention] Pollution Prevention N BMP C153: Material Delivery, Storage and BMP C153: Material Delivery, Storage, and o N Containment Containment 3 BMP C154: Concrete Washout Area BMP C154: Concrete Washout Area N 0 L BMP C160: Certified Erosion and Sediment BMP C160: Certified Erosion and Sediment U 0 Control Lead Control Lead E BMP C162: Scheduling BMP C162: Scheduling r r Q II-4.2 - Runoff Conveyance and Treatment BMPs II-3.1 A Summary of Construction Stormwater BMPs BMP C200: Interceptor Dike and Swale BMP C200: Interceptor Dike and Swale a BMP C201: Grass -Lined Channels BMP C201: Grass -Lined Channels https://fortress.wa.gov/ecy/ershare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/Crosswalk2014-2019.htm%3FTOIP Packet Pg. 191 5/11/2021 Crosswalk: 2014 - 2019 SWMMWW Dept. of 2.4.g Location of Content within the 2014 SWMMWW Location of Content within the 20 19 SWMMWW BMP C202: Channel Lining BMP C202: Rip La Channel Lining aD BMP C203: Water Bars BMP C203: Water Bars a a BMP C204: Pipe Slope Drains BMP C204: Pipe Slope Drains M 00 BMP C205: Subsurface Drains BMP C205: Subsurface Drains U 0 U BMP C206: Level Spreader BMP C206: Level Spreader w BMP C207: Check Dams BMP C207: Check Dams 0 a� BMP C208: Triangular Silt Dike (TSD) E m (Geotextile-Encased Check Dam) BMP C208: Triangular Silt Dike (TSD), c CU BMP C209: Outlet Protection BMP C209: Outlet Protection r CU 3 BMP C220: Storm Drain Inlet Protection BMP C220: Inlet Protection E 0 BMP C231: Brush Barrier BMP C231: Brush Barrier o r- 0 BMP C232: Gravel Filter Berm BMP C232: Gravel Filter Berm BMP C233: Silt Fence BMP C233: Silt Fence L a BMP C234: Vegetated Strip BMP C234: Vegetated Strip BMP C235: Wattles BMP C235: Wattles BMP C236: Vegetative Filtration BMP C236: Vegetative Filtration N BMP C240: Sediment Trap BMP C240: Sediment Trap N BMP C241: Temporary Sediment Pond BMP C241: Sediment Pond (Temporary_) i BMP C250: Construction Stormwater Chemical BMP C250: Construction Stormwater o L Treatment Chemical Treatment BMP C251: Construction Stormwater Filtration BMP C251: Construction Stormwater E Filtration BMP C252: High pH Neutralization Using CO2 BMP C252: Treating and Disposing of High r pH Water a BMP C253: pH Control for High pH Water BMP C252: Treating and Disposing of High pH Water E Volume II Resource Materials References a https://fortress.wa.gov/ecy/ershare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/Crosswalk2014-2019.htm%3FTOIP Packet Pg. 192 5/11/2021 Crosswalk: 2014 - 2019 SWMMWW Dept. of 2.4.g Location of Content within the 2014 SWMMWW Location of Content within the 20 19 SWMMWW Appendix II -A: Recommended Standard Notes for Appendix 11-A: Recommended Standard Erosion Control Plans Notes for Construction SWPPP Drawings r Appendix II-B: Background Information on Chemical BMP C250: Construction Stormwater Chemical Treatment Treatment M co U Volume III Content w aD Volume III Acknowledgments Acknowledgments III-1 -Introduction (no content in this section) c E a� III-1.1 -Purpose of this Volume I-1.5 Types of Best Management Practices .(BMPs) for Stormwater Management CU III-1.2 - Content and Organization of this Volume 1-1.1 About This Manual 3 III-1.3 - How to Use this Volume I-1.1 About This Manual o III-2 - Hydrologic Analysis III-2.1 An Overview of Hydrologic Analysis 00 0 III-2.1 -Minimum Computational Standards III-2.1 An Overview of Hydrologic Analysis a� III-2.2 - Western Washington Hydrology Model III-2.2 Continuous Simulation Models y a III-2.3 - Single Event Hydrograph Method 111-2.3 Single Event Hydrograph Method III-2.4 - Closed Depression Analysis III-2.5 Closed Depression Analysis III-3 -Flow Control Design various individual BMPs within Volume V N III-3.1 - Roof Downspout Controls p V-4.1 Introduction to Roof Downspout BMPs N i III-3.1.1 - Downspout Full Infiltration Systems (BMP T5.10A) BMP T5.10A: Downspout Full Infiltration N 0 L III-3.1.2 - Downspout Dispersion Systems (BMP Ui T5.10B) BMP T5.1013: Downspout Dispersion Systems aD E III-3.1.3 -Perforated Stub Out Connections BMP T5.10C: Perforated Stub -out (BMP T5.10C) Connections a w III-3.2 -Detention Facilities V-12.1 Introduction to Detention BMPs c E III-3.2.1 -Detention Ponds BMP DA : Detention Ponds a III-3.2.2 - Detention Tanks BMP D.2: Detention Tanks https://fortress.wa.gov/ecy/ershare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/Crosswalk2014-2019.htm%3FTocP Packet Pg. 193 5/11/2021 Crosswalk: 2014 - 2019 SWMMWW Dept. of 2.4.g Location of Content within the 2014 SWMMWW Location of Content within the 20 19 SWMMWW III-3.2.3 - Detention Vaults BMP D.3: Detention Vaults aD III-3.2.4 -Control Structures V-12.2 Control Structure Design -a a III-3.2.5 - Other Detention Options V-12.3 Other Detention Design Options M co III-3.3 - Infiltration Facilities for Flow Control and for v Treatment (no content in this section) w aD III-3.3.1 -Purpose V-5.1 Introduction to Infiltration BMPs 0 U III-3.3.2 -Description V-5.1 Introduction to Infiltration BMPs E a� a� III-3.3.3 -Applications V-5.1 Introduction to Infiltration BMPs = III-3.3.4 - Steps for the Design of Infiltration, Facilities - Simplified Approach V-5.2 Infiltration BMP Design Steps E L III-3.3.5 - Site Characterization Criteria V-5.5 Site Characterization Criteria for ° Infiltration o III-3.3.6 - Design Saturated Hydraulic V-5.4 Determining the Design Infiltration Rate o w Conductivity - Guidelines and Criteria of the Native Soils c a� y III-3.3.7 - Site Suitability Criteria (SSC) V-5.6 Site Suitability Criteria (SSC) a V-5.2 Infiltration BMP Design Steps III-3.3.8 - Steps for Designing Infiltration and Facilities - Detailed Approach V-5.4 Determining the Design Infiltration Rate of o N the Native Soils 0 III-3.3.9 -General Design, Maintenance, and V-5.3 General Design Criteria for Infiltration Construction Criteria for Infiltration Facilities BMPs f° 3 III-3.3.10 -Infiltration Basins BMP T7.10: Infiltration Basins v i c9 III-3.3.11 -Infiltration Trenches BMP T7.20: Infiltration Trenches aD E III-3.4 - Stormwater-related Site Procedures and BMP T7.30: Bioretention and Q Design Guidance for Bioretention and Permeable Pavement BMP T5.15: Permeable Pavements a E Volume III References References a Volume III Resource Materials References I https://fortress.wa.gov/ecy/ershare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/Crosswalk2014-2019.htm%3FTo,P Packet Pg. 194 5/11/2021 Crosswalk: 2014 - 2019 SWMMWW Dept. of 2.4.g Location of Content within the 2014 SWMMWW Location of Content within the 20 19 SWMMWW Appendix III -A: Isopluvial Maps for Design Storms Appendix III-B: Isopluvial Maps for Design Storms a� Appendix III-B: Western Washington Hydrology Model - Information, Assumptions, and Computation Steps III-2.2 Continuous Simulation Models 0 Appendix III-C: Washington State Department of Ecology M co Low Impact Development Flow Modeling Guidance various individual BMPs within Volume V Q U W_ Volume IV Content o U Volume IV Acknowledgments Acknowledgments c E m a, IV-1 -Introduction (no content in this section) R IV-1.1 - Purpose of this Volume 111-1.1 Choosing Your Source Control BMPs 3 IV-1.2 - Content and Organization of this Volume I-1.1 About This Manual o IV-1.3 -How to Use this Volume III-1.1 Choosing Your Source Control BMPs r_ 0 IV-1.4 -Operational and Structural Source Control 1-1.5 Types of Best Management Practices c BMPs for Stormwater Management .(BMPs) L a IV-1.5 - Treatment BMPs for Specific Pollutant � Sources Executive Summary of Volume IV IV-1.6 - Distinction between Applicable BMPs and Recommended BMPs III-1.1 Choosing Your Source Control BMPs a) r O N IV-1.7 -Regulatory Requirements Affecting 1-2 Relationship of This Manual to Permits, o Stormwater Pollutant Control Requirements, and Programs N I IV-2 - Selection of Operational and Structural Source Control BMPs III-1.1 Choosing Your Source Control BMPs 0 o U IV-2.1 - Applicable (Mandatory) Operational Source IV-1 Source Control BMPs Applicable to All I Control BMPs Sites E t IV-2.2 -Pollutant Source -Specific BMPs III-1.1 Choosing Your Source Control BMPs a S401 BMPs for the Building, Repair, and S401 BMPs for the Building Rep air, and w Maintenance of Boats and Ships Maintenance of Boats and Ships E S402 BMPs for Commercial Animal Handling S402 BMPs for Commercial Animal Handling a Areas Areas I https://fortress.wa.gov/ecy/ershare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/Crosswalk2014-2019.htm%3FTocP Packet Pg. 195 5/11/2021 Crosswalk: 2014 - 2019 SWMMWW Dept. of 2.4.g Location of Content within the 2014 SWMMWW Location of Content within the 20 19 SWMMWW S403 BMPs for Commercial Composting S403 BMPs for Commercial Composting S404 BMPs for Commercial Printing Operations S404 BMPs for Commercial Printing Operations S405 BMPs for Deicing and Anti -Icing S405 BMPs for Deicing and Anti -Icing M Operations - Airports and Streets Operations for Airports co U S406 BMPs for Streets/Highways S406 BMPs for Streets and Highways w aD S407 BMPs for Dust Control at Disturbed Land S407 BMPs for Dust Control at Disturbed 'a ° Land Areas and Unpaved Roadways and Areas and Unpaved Roadways and Parking Lots Parking Lots E a� a� S408 BMPs for Dust Control at Manufacturing S408 BMPs for Dust Control at Manufacturing Areas Areas a� r S409 BMPs for Fueling at Dedicated Stations S409 BMPs for Fueling At Dedicated Stations E 0 S410 BMPs for Illicit Connections to Storm S410 BMPs for Correcting Illicit Discharges to y 0 Drains Storm Drains r_ 0 w S411 BMPs for Landscaping and S411 BMPs for Landscaping and Lawn / y Lawn/Vegetation Management Vegetation Management L a S412 BMPs for Loading and Unloading Areas S412 BMPs for Loading and Unloading Areas for Liquid or Solid Material for Liquid or Solid Material S413 BMPs for Log Sorting and Handling S413 BMPs for Log Sorting and Handling r O S414 BMPs for Maintenance and Repair of S414 BMPs for Maintenance and Repair of � Vehicles and Equipment Vehicles and Equipment o N I S415 BMPs for Maintenance of Public and S415 BMPs for Maintenance of Public and f° Private Utility Corridors and Facilities Private Utility Corridors and Facilities N 0 L S416 BMPs for Maintenance of Roadside S416 BMPs for Maintenance of Roadside cal Ditches c Ditches a� E S417 BMPs for Maintenance of Stormwater S417 BMPs for Maintenance of Stormwater Drainage and Treatment Systems Drainage and Treatment Systems a w S418 BMPs for Manufacturing Activities - S418 BMPs for Manufacturing Activities - c E Outside Outside a S419 BMPs for Mobile Fueling of Vehicles and S419 BMPs for Mobile Fueling of Vehicles Heavy Equipment and Heavy Equipment ittps://fortress.wa.gov/ecy/ershare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/Crosswalk2014-2019.htm%3FTo,P Packet Pg. 196 5/11/2021 Crosswalk: 2014 - 2019 SWMMWW Dept. of 2.4.g Location of Content within the 2014 SWMMWW Location of Content within the 20 19 SWMMWW S420 BMPs for Painting/Finishing/Coating of S420 BMPs for Painting/Finishing/Coating of Vehicles/Boats/Buildings/Equipment Vehicles/Boats/Buildings/Equipment r S421 BMPs for Parking and Storage of Vehicles S421 BMPs for Parking and Storage of and Equipment Vehicles and Equipment M C6 S422 BMPs for Railroad Yards S422 BMPs for Railroad Yards o U W S423 BMPs for Recyclers and Scrap Yards S423 BMPs for Recyclers and Scrap Yards 0 S424 BMPs for Roof/Building Drains at S424 BMPs for Roof / Building Drains at Manufacturing and Commercial Buildings Manufacturing and Commercial Buildings E a� S425 BMPs for Soil Erosion and Sediment S425 BMPs for Soil Erosion and Sediment CU Control at Industrial Sites Control at Industrial Sites a� r S426 BMPs for Spills of Oil and Hazardous S426 BMPs for Spills of Oil and Hazardous E Substances Substances ° 4- S427 BMPs for Storage of Liquid, Food Waste, S427 BMPs for Storage of Liquid, Food r- 0 or Dangerous Waste Containers Waste, or Dangerous Waste Containers a c S428 BMPs for Storage of Liquids in Permanent S428 BMPs for Storage of Liquids in L Aboveground Tanks g Permanent Aboveground Tanks a S429 BMPs for Storage or Transfer (Outside) of S429 BMPs for Storage or Transfer (Outside). Solid Raw Materials, Byproducts, or Finished of Solid Raw Materials, Byproducts, or Products Finished Products r O N S430 BMPs for Urban Streets S430 BMPs for Urban Streets 0 S431 BMPs for Washing and Steam Cleaning S431 BMPs for Washing and Steam Cleaning c'ql Vehicles/Equipment/Building Structures Vehicles / Equipment / Building Structures S432 BMPs for Wood Treatment Areas S432 BMPs for Wood Treatment Areas i S433 BMPs for Pools, Spas, Hot Tubs, and S433 BMPs for Pools, Spas, Hot Tubs, and c9 Fountains Fountains E t Volume IV References References Q w Appendix IV -A: Urban Land Uses and Pollutant Appendix IV -A: Urban Land Uses and c E Generating Sources Pollutant Generating Sources a Appendix IV-B: Stormwater Pollutants and Their Adverse 1-1.4 Stormwater Pollutants and Their Impact Adverse Impact ittps://fortress.wa.gov/ecy/ershare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/Crosswalk2014-2019.htm%3FTo,P Packet Pg. 197 5/11/2021 Crosswalk: 2014 - 2019 SWMMWW Dept. of 2.4.g Location of Content within the 2014 SWMMWW Location of Content within the 20 19 SWMMWW Appendix IV-C: Recycling/Disposal of Vehicle Outdated / deleted. References to this Fluids/Other Wastes appendix are now referred to Ecology's hazardous waste site. Appendix IV-D: Regulatory Requirements That Impact I-2 Relationship of This Manual to Permits, Stormwater Programs Requirements, and Programs M co Appendix IV-E: NPDES Stormwater Discharge Permits 1-2 Relationship of This Manual to Permits, o Requirements, and Programs Appendix IV-F: Example of an Integrated Pest S435 BMPs for Pesticides and an Integrated w Management Program Pest Management Program Appendix IV-G: Recommendations for Management of Appendix IV-B: Management of Street Waste E Street Wastes Solids and Liquids c CU Volume IV Resource Materials - Management of Street L Wastes References r 3 E L 0 Volume V Content y 0 c Volume V Acknowledgments Acknowledgments a c V-1 -Introduction (no content in this section) a� L a V-1.1 - Purpose of this Volume Executive Summary of Volume V V-1.2 - Content and Organization of this Volume Executive Summary of Volume V V-1.3 -How to Use this Volume Executive Summary of Volume V o N V-1.4 - Runoff Treatment Facilities various BMP group introductions within Volume V N V-2 - Treatment Facility Selection Process 111-1.2 Choosing Your Runoff Treatment BMPs 3 V-2.1 - Step -by -Step Selection Process for o Treatment Facilities 111-1.2 Choosing Your Runoff Treatment BMPs 0 i c� V-2.2 -Other Treatment Facility Selection Factors III-1.2 Choosing Your Runoff Treatment BMPs E V-3 -Treatment Facility Menus 111-1.2 Choosing Your Runoff Treatment BMPs r a V-3.1 -Guide to Applying Menus 111-1.2 Choosing Your Runoff Treatment BMPs E V-3.2 -Oil Control Menu III-1.2 Choosing Your Runoff Treatment BMPs 2 a V-3.3 - Phosphorus Treatment Menu III-1.2 Choosing Your Runoff Treatment BMPs https://fortress.wa.gov/ecy/ershare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/Crosswalk2014-2019.htm%3FTo,P Packet Pg. 198 5/11/2021 Crosswalk: 2014 - 2019 SWMMWW Dept. of 2.4.g Location of Content within the 2014 SWMMWW Location of Content within the 20 19 SWMMWW V-3.4 - Enhanced Treatment Menu III-1.2 Choosing Your Runoff Treatment BMPs aD V-3.5 -Basic Treatment Menu III-1.2 Choosing Your Runoff Treatment BMPs -a a V-4 - General Requirements for Stormwater Facilities V-1 General BMP Design M co V-4.1 - Design Volume and Flow III-2.6 Sizing Your Runoff Treatment BMPs v 0 U V-4.2 - Sequence of Facilities V-1.1 Sequence of Runoff Treatment and w Detention BMPs 'a V-4.3 -Setbacks, Slopes, and Embankments V-1.2 Setbacks, Slopes, and Embankments 0 W V-4.4 - Facility Liners V-1.3 Liners and Geotextiles E V-4.5 -Hydraulic Structures V-1.4 Hydraulic Structures c L d V-4.6 - Maintenance Standards for Drainage Facilities Appendix VA BMP Maintenance Tables E 0 V-5 - On -Site Stormwater Management (no content in this section) c 0 V-5.1 -Purpose I-1.5 Types of Best Management Practices w .(BMPs) for Stormwater Management V-5.2 -Application BMP T5.30: Full Dispersion a V-5.3 - Best Management Practices for On -Site Stormwater Management various individual BMPs within Volume V V-5.3.1 - On -Site Stormwater Management 1-3.4.5 MR5: On -Site Stormwater BMPs Management r N BMP T5.10A: Downspout Full Infiltration BMP T5.10A: Downspout Full Infiltration N i BMP T5.10B: Downspout Dispersion Systems BMP T5.1013: Downspout Dispersion Systems N 0 L BMP T5.10C: Perforated Stub -out BMP T5.10C: Perforated Stub -out U Connections Connections a E BMP T5.11: Concentrated Flow Dispersion BMP T5.11: Concentrated Flow Dispersion r Q BMP T5.12: Sheet Flow Dispersion BMP T5.12: Sheet Flow Dispersion E BMP T5.13: Post -Construction Soil Quality BMP T5.13: Post -Construction Soil Quality_ and Depth and Depth a BMP T5.14A: Rain Gardens BMP T5.14: Rain Gardens I https://fortress.wa.gov/ecy/ershare/wq/Permits/Flare/20l9SWMMWW/2019SWMMWW.htm#Topics/Crosswalk2014-2019.htm%3FTocP Packet Pg. 199 5/11/2021 Crosswalk: 2014 - 2019 SWMMWW Dept. of 2.4.g Location of Content within the 2014 SWMMWW Location of Content within the 20 19 SWMMWW BMP T5.14B: Bioretention BMP T7.30: Bioretention aD BMP T5.15: Permeable Pavements BMP T5.15: Permeable Pavements a a BMP T5.16: Tree Retention and Tree o Planting BMP T5.16: Tree Retention and Tree PlantingCO U BMP T5.17: Vegetated Roofs BMP T5.17: Vegetated Roofs w aD BMP T5.18: Reverse Slope Sidewalks BMP T5.18: Reverse Slope Sidewalks 0 U BMP T5.19: Minimal Excavation Foundations BMP T5.19: Minimal Excavation Foundations m BMP T5.20: Rainwater Harvesting BMP T5.20: Rainwater Harvesting a, CU BMP T5.30: Full Dispersion BMP T5.30: Full Dispersion 3 V-5.3.2 -Site Design BMPs V-2.1 Introduction to Site Design BMPs L 0 v/ BMP T5.40: Preserving Native Vegetation BMP T5.40: Preserving Native Vegetation o c 0 BMP T5.41: Better Site Design BMP T5.41: Better Site Design V-6 -Pretreatment (no content in this section) L a V-6.1 -Purpose V-9.1 Introduction to Pretreatment BMPs V-6.2 - Application V-9.1 Introduction to Pretreatment BMPs V-6.3 - Best Management Practices (BMPs) for c Pretreatment V-9.1 Introduction to Pretreatment BMPs N 0 BMP T6.10: Presettling Basin BMP T6.10: Presettling Basin V-7 - Infiltration and Bioretention Treatment Facilities (no content in this section) N 0 L V-7.1 - Purpose V-5.1 Introduction to Infiltration BMPs Ui � V-7.2 -General Considerations V-5.1 Introduction to Infiltration BMPs E t V-7.3 -Applications V-5.1 Introduction to Infiltration BMPs r a V-7.4 - Best Management Practices (BMPs) for w Infiltration and Bioretention Treatment V-5.1 Introduction to Infiltration BMPs E BMP T7.10: Infiltration Basins BMP T7.10: Infiltration Basins a https://fortress.wa.gov/ecy/ershare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/Crosswalk2014-2019.htm%3FTo,P Packet Pg. 200 5/11/2021 Crosswalk: 2014 - 2019 SWMMWW Dept. of 2.4.g Location of Content within the 2014 SWMMWW Location of Content within the 20 19 SWMMWW BMP T7.20: Infiltration Trenches BMP T7.20: Infiltration Trenches aD BMP T7.30: Bioretention Cells, Swales, and Planter Boxes BMP T7.30: Bioretention 0 M BMP T7.40: Compost -Amended Vegetated Filter BMP T7.40: Compost -Amended Vegetated 00 Strips (CAVFS) Filter Strips (CAVES) o U V-8 -Filtration Treatment Facilities V-6.1 Introduction to Filtration BMPs W_ aD 0 V-8.1 -Purpose V-6.1 Introduction to Filtration BMPs a� E V-8.2 -Description V-6.1 Introduction to Filtration BMPs V-8.3 -Performance Objectives V-6.1 Introduction to Filtration BMPs CU d V-8.4 - Applications and Limitations V-6.1 Introduction to Filtration BMPs CU E L V-8.5 - Best Management Practices (BMPs) for C y Sand Filtration (no content in this section) o c 0 BMP T8.10: Basic Sand Filter Basin BMP T8.10: Basic Sand Filter Basin w c a� y BMP T8.11: Large Sand Filter Basin BMP T8.11: Large Sand Filter Basin a BMP T8.20: Sand Filter Vault BMP T8.20: Sand Filter Vault BMP T8.30: Linear Sand Filter BMP T8.30: Linear Sand Filter BMP T8.40: Media Filter Drain (previously referred N to as the Ecology Embankment) BMP T8.40: Media Filter Drain 0 N V-9 - Biofiltration Treatment Facilities V-7.1 Introduction to Biofiltration BMPs Y� 3 V-9.1 -Purpose V-7.1 Introduction to Biofiltration BMPs N 0 L U V-9.2 - Applications V-7.1 Introduction to Biofiltration BMPs V-9.3 -Site Suitability V-7.1 Introduction to Biofiltration BMPs E t V-9.4 -Best Management Practices V-7.1 Introduction to Biofiltration BMPs a w BMP T9.10: Basic Biofiltration Swale BMP T9.10: Basic Biofiltration Swale E BMP T9.20: Wet Biofiltration Swale BMP T9.20: Wet Biofiltration Swale a BMP T9.30: Continuous Inflow Biofiltration Swale BMP T9.30: Continuous Inflow Biofiltration Swale https://fortress.wa.gov/ecy/ershare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/Crosswalk2014-2019.htm%3FTOIP Packet Pg. 201 5/11/2021 Crosswalk: 2014 - 2019 SWMMWW Dept. of 2.4.g Location of Content within the 2014 SWMMWW Location of Content within the 20 19 SWMMWW BMP T9.40: Basic Filter Strip BMP T9.40: Vegetated Filter Strip aD V-10 -Wetpool Facilities V-8.1 Introduction to Wetpool BMPs a a V-10.1 - Purpose V-8.1 Introduction to Wetpool BMPs M co V-10.2 - Application V-8.1 Introduction to Wetpool BMPs U 0 U V-10.3 - Best Management Practices (BMPs) for w Wetpool Facilities V-8.1 Introduction to Wetpool BMPs o U BMP T10.10: Wetponds - Basic and Large BMP T10.10: Wetponds - Basic and Large a� BMP T10.20: Wetvaults BMP T10.20: Wetvaults = CU a BMP T10.30: Stormwater Treatment Wetlands BMP T10.30: Stormwater Treatment Wetlands 3 BMP T10.40: Combined Detention and Wetpool BMP T10.40: Combined Detention and c Facilities Wetpool Facilities y 4- 0 V-11 -Oil and Water Separators V-13.1 Introduction to Oil and Water 0 Separator BMPs a V-11.1 - Purpose of Oil and Water Separators V-13.1 Introduction to Oil and Water y Separator BMPs L V-11.2 - Description V-13.1 Introduction to Oil and Water a Separator BMPs V-11.3 - Performance Objectives V-13.1 Introduction to Oil and Water Separator BMPs V-11.4 - Applications/Limitations V-13.1 Introduction to Oil and Water Separator BMPs o V-11.5 - Site Suitability V-13.1 Introduction to Oil and Water N Separator BMPs o V-11.6 - Design Criteria - General Considerations V-13.1 Introduction to Oil and Water Ni Separator BMPs V-11.7 - Oil and Water Separator BMPs V-13.1 Introduction to Oil and Water N Separator BMPs o BMP T11.10: API (Baffle type) Separator Bay BMP T11.10: API (Baffle type) Separator Ui � BMP T11.11: Coalescing Plate (CP) Separator Bay BMP T11.11: Coalescing Plate (CP) Separator E V-12 - Emerging Technologies (no content in this section) r Q V-12.1 - Background V-10.1 Introduction to Manufactured C Treatment Devices as BMPs E V-12.2 -Ecology Role in Evaluating Emerging V-10.3 Approval Process for Manufactured a Technologies Treatment Devices https://fortress.wa.gov/ecy/ershare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/Crosswalk2014-2019.htm%3FTOIP Packet Pg. 202 5/11/2021 Crosswalk: 2014 - 2019 SWMMWW Dept. of 2.4.g Location of Content within the 2014 SWMMWW Location of Content within the 20 19 SWMMWW V-12.3 - Evaluation of Emerging Technologies V-10.3 Approval Process for Manufactured Treatment Devices a� V-12.4 - Assessing Levels of Development of V-10.2 Use Level Designations of a Emerging Technologies Manufactured Treatment Devices 0 V-12.5 -Emerging Technologies for Stormwater V-10.3 Approval Process for Manufacturedco M Treatment and Control Options Treatment Devices o U W Volume V References References v aD 0 Appendix V-A: Basic Treatment Receiving Waters Appendix 111-A: Basic Treatment Receiving Waters (D E Appendix V-B: Recommended Modifications to ASTM D 2434 When Measuring Hydraulic Conductivity for BMP T7.30: Bioretention a Bioretention Soil Mixes L d Appendix V-C: Geotextile Specifications V-1.3.4 Geotextile Specifications E 0 Appendix V-D: Turbulence and Short -Circuiting Factor BMP T11.10: API (Baffle type) Separator o c Appendix V-E: Recommended Newly Planted Tree ° w Species for Flow Control Credit BMP T5.16: Tree Retention and Tree Planting y L a Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 https://fortress.wa.gov/ecy/ershare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/Crosswalk2014-2019.htm%3FTocP Packet Pg. 203 2.4.h 2022 Stormwater Management Code (ECDC 18,30) Update Presented by Zachary Richardson, Stormwater Engineer Packet Pg. 204 2.4.h L • NPDES Permit with State requires codes to protect € surfaces water from development which meets or o exceeds standards prescribed by Ecology. o -, -,f - • New permit requires that the City update to i newest Ecology standard by July 2022. o. Why are we • Staff aiming for effective date of January 1, 2022IL L u d at i n the for clarity in applicability timelines. p g code now.0. • Ecology's newest manual (2019 SWMMWW) has minimal substantive changes since previous versi (2014); most revisions are organizational changes o W • See Ecology documents Executive Summary of th 2019 Revisions and Crosswalk: 2014-2019 SWMMWW for additional information of Ecology a driven changes. a Packet Pg. 205 2.4.h L a.+ • Ecology issues their manual (2019 SWMMWW) 0 U) • City makes minor local modifications via the 4- 0 Edmonds Stormwater Addendum (Addendum) How is ECDC a related to • City updates ECDC 18.30 to adopt the new manual as modified in the Addendum N L a Ecology Some provisions are required by Ecology Manual?CL Some items are optional add-ons for City of o Edmonds - M 0 • City provisions cannot be less stringent than Ecolo W =� standard and can not be less stringent than previo E version (without Ecology approval) ' a Q Packet Pg. 206 2.4.h CU 3 • Drainage mitigation is required when projects exceed o certain thresholds of new plus replaced hard surfaces o and/or clearing limits. s W • Hard surfaces are traditional impervious surfaces, IOIU other compacted surfaces including gravel roadways a and pervious pavements. o • Replaced hard surfaces are any surfaces where the subgrade material below the surface is exposed . Drainage temporarily during the construction operation. • Category 1— Minimum Requirements (MR) 1-5 appl Review 101 . 2,000 SF new plus replace hard surfaces, OR • 7,000 SF of land disturbing activity (clearing) • Category 2—Minimum Requirements 1-9apply • 5,000 SF new plus replace hard surfaces, OR • Converts 0.75 acres of vegetation to lawn/landscaped area, • Converts 2.5 acres of native vegetation to pasture Packet Pg. 207 2.4.h L a.+ • Minimum Requirement #5 (LID) 0 0 • Applies to all projects that require drainage review (over 2,001 SF hard surfaces). *MEW • Focuses on erosion flows; 2-year storm and below. y • Requires the use of infiltration if feasible a • Predominant way we get storm water mitigation in Edmonds cc • Minimum Requirement #6 (Water quality) L Requires 5,000 SF of pollution generating hard surfaces (ie.�- Drainage drivable pavement; does not include roofs in most cases) , o Requires treatment of runoff specific to ;removing Review 101 contaminants.CL 0 • Minimum Requirement #7 (Flow control) 3 • Requires 10,000 SF of hard surfaces (or more than 0.1 cfs W increase in discharge from site) • Big vaults/detention; this is the traditional way of storm watt management where we try to match historic flow rates. • Infiltration is required to be used for flow control if applicabl Packet Pg. 208 2.4.h L a.+ • Switched permit tracking systems at beginning of 2020; reviewed single family building permit data since that o *MOdate through the start of June 2021.` • This didn't capture plats as a whole project but reflects the L mitigation required for each individual home within a plat. a 0 • Focused on main BMP where multiple BMPs were proposed. C d • 52 projects required drainage review - How's i it • 2 applied dispersion as main BMP C. working? • 22 applied an infiltration -based BMP o - N 0 • 5 applied a perforated pipe connection o • 22 applied Edmonds -specific detention BMPAO W' • 1 qualified for direct discharge ••E, .r V 1r Q Packet Pg. 209 2.4.h L a.+ Most changes are updates to match Ecology E 0 reorganization and/or to provide clarity where staff - have experienced commonly missed or misinterpreted information by manual users & designers. 0 L See 2022 ECDC 18.30 and Stormwater Addendum Summary of Changes in agenda packet • Direction from Ecology (Orange) = Ecology prescribed/requir - What's • Direction from Staff (White) = Staff -proposed clarification, reorganization, or update without substantial change/impact Changing? • Direction from Staff Green = Staff- ro osed chan a wit ( ) p p g potential impacts • Staff seek direction on staff -proposed changes with potential impacts prior to moving code for State approval and permitting. • Department of Commerce and SEPA approval required prior formal Council adoption. Packet Pg. 210 2.4.h Change 1: New connections of existing hard surfaces L a.+ Old: Current code allows for connection of existing hard o surfaces on case -by -case basis with a focus on maintaining - City pipe capacity. diMM4 o M New: Staff propose revisions to require new connections' 01 existing hard surfaces to be treated like new hard surfaces requiring full drainage mitigation. • Note that this is specific to new connections; where residents have an existing connection, they are permitted to replace the connection in -kind without any mitigation requirements. ,y • Staff Opinion: These new connections of existing surfaces still new or altered impacts to the City system and any surfaces water they drain to; they should be mitigated for new impacts. • Potential Impacts: This may limit homeowner options w� working on homes without development or expansion. However, the impacts of allowing every pre -drainage -cod residence or business to connect to our system would be continuation of the negative impacts of unmitigated histo development and detrimental to staff ability to manage the capacity of our systems in the future. Packet Pg. 211 2.4.h L • Old: Current code recognizes the Edmonds Way o drainage basin as a partial direct discharge basin with - reduced requirements for LID (MR #5) and flow contra .o y Change #2: (MR #7) � �"��� � •' .. • New: Staff propose revisions to remove all exemption! a Removing for the Edmonds Way basin, resulting in equal 0 Edmonds Wayas application of all drainage code requirements to the Edmonds Way basin. a direct • Staff Opinion: The Edmonds Way drainage pipe a o (WSDOT) is known to overflow to the Edmonds Mars 1 di sc h a rge basin.under certain conditions; since this demonstrates a D capacity issue and now discharges to a non-manmad 0 M water body, the direct discharge exemption should no, longer apply. W • Potential Impacts: This simply means that projects within the Edmonds Way basin comply with the exac same requirement as the rest of the City. a -r W. le = 16 Q Packet Pg. 212 2.4.h L • Old: Current code applies the drainage code uniformly to i areas of City, including the Perrinville Creek Basin. o • New: Staff propose revisions to increase the retrofit 4- requirement for LID and increase the flow control standan 0 within the Perrinville Creek basin (only). ,�-� Change #3 Retrofit (applies to existing unmitigated surfaces to remain): 2500 50% a Increasing 0Flow control: Match 50-year peak => Match 100-year peak (ie. Kii County Level 3 Standard) ofprotection Staff Opinion. The Perrinville has been beaten up by past Perrinville development and needs better protections. The change it o flow control standard is typical for impacted water ways all Creek. the retrofit requirement attempts to rectify some of the p� Qt abuses on the creek. Staff believe its fair to ask the resid 0 M who have directly benefitted from the impacts on the cr to chip in a little extra towards its recovery. W • Potential Impacts: Flow control will have minimal impa larger projects will have larger detention facilities with E minimal impacts and cost on already large budgets. However, the retrofit requirement has the potential to a impact homeowners who are not necessarily developing a I may become cost -limiting to smaller projects in this basin. a Packet Pg. 213 2.4.h Change #4 Detention preferred over Perforated Pipes 0 L a.+ Old: Current code adopted the Ecology BMP list for MR #5 E and then added an Edmonds -specific detention BMP to the CO end of the list, making its priority less than that of a o perforated pipe connection. • VOL. W New: Staff propose revisions to elevate the Edmonds -specs detention BMP to be considered before a perforated pipe a connection. o • Staff Opinion: Perforated pipes connection are only used when infiltration is already found undesirable for some reason; because of this fact, they are of very little mitigation benefit and often get proposed in dangerous or undesirable locations. Staff have run flow comparisons to demonstrat that the detention option generates far more desirable decreases in the flow rates for sites this condition would apply to. : -- • Potential Impacts: At a minimum detention would be anticipated in nearly all cases where drainage review is Aq required. Detention systems may add some cost to developing compared to the perforated pipe connections by will go much further in protecting the City system and surfaces waters. Packet Pg. 214 2.4.h L a.+ • Staff is requesting comments from the City Council. o 0 • We are requesting comments now, prior to beginning the o permitting and approval process. W ° N • Approvals Needed - = y L J ...r r • Department of Commerce o • SEPA d L a • No Ecology review • Public Input What Next? • SEPA comment period required • Public hearing required before final approval/adoption • Additional workshops, as directed/if needed. • Questions/concerns: Zachary.Richardson@edmondswa.gov Packet Pg. 215